Lower Alkaline Phosphatase Levels Research Articles

MON-LB71 Adult Hypophosphatasia and Postmenopausal Osteoporosis: A Challenging Case

Introduction: Hypophosphatasia (HPP) is a rare disease that cause osteomalacia and premature tooth loss due to abnormal bone mineralization. The clinical presentation ranges from severe neonatal and infantile HPP with a high morbidity and mortalilty to mild Adult HPP. The ranging spectrum is possibly due to autosomal recessive versus autosomal dominant missense mutations at the gene that encodes TNSALP. The hallmark of the disease is a low serum total alkaline phosphatase level (ALP). It is important to diagnose adult HPP particularly to refrain from treating with bone antiresorptive medications. Low levels of alkaline phosphatase generally are undectected in the adult population even in patients with osteoporosis and fractures. We describe a case of a woman with postmenopausal osteoporosis without fractures diagnosed with adult HPP. The clinical course and management is described below. Case Description: A 62 y.o. women was referred for evaluation and treatment of osteoporosis. She had no fractures, including during childhood, no history of premature deciduous teeth loss, dental problems or nephrolithiasis. No family history of osteoporosis or fractures. Menopause at age 48 without hormone replacement therapy. Evaluation for secondary causes of osteoporosis was normal including serum TSH, calcium, phosphate, PTH, 24 hours urinary calcium and vitamin D-25. ALP ranged from 33-40 U/L (nl 37-126) before therapy. She was treated with raloxifene for 2 years. Therapy was switched to alendronate due to a decrease in bone density. She subsequently treated with alendronate for 5 years until 5/2012. Due to a decrease in bone density alendronate therapy was reinstituted between Jan 2013-Jan 2016 but in spite of therapy and a CTX level of 333 pg/ml bone density in the spine decreased significantly. In view of the low ALP and decreasing bone density while on bisphosphonate and a high B6 level (B6= 37 nl: -27) a genetic test for HPP and a compound heterozygote mutation in ALPL gene was detected. Her daughter was also found to have low ALP and carries the same mutation. Bone density has been stable since bisphosphonate therapy was stopped (spine T -3.2, LT femoral neck T -2.9) CTX 360 pg/ml. Recently therapy with raloxifene was initiated in view of the low bone density and high risk of fractures. Conclusion: The proper diagnosis and management of patients with adult HPP is challenging because the diagnosis may be missed in patients with borderline low ALP and on the other hand the proper managent of osteoporosis in these patients is not known.

MON-341 New Diagnosis of Hypophosphatasia in a 79-Year-Old Woman with Low Bone Density

Introduction: Hypophosphatasia is a rare metabolic bone disease caused by one of several mutations in the ALPL gene which encodes tissue nonspecific alkaline phosphatase (ALP). It is usually diagnosed in childhood and can have a heterogenous clinical presentation depending on the extent of enzyme deficiency. Here we report the oldest known patient with hypophosphatasia. Clinical Case: A 79-year-old woman with a history of medullary thyroid cancer (MTC) in remission, was referred to our metabolic bone disease clinic for the evaluation and treatment of osteopenia. She had suffered from numerous musculoskeletal complaints for several years and had received a diagnosis of polymyalgia rheumatica. However, her symptoms persisted despite a six month trial of prednisone. Although she had developed dental caries at a young age, she denied premature tooth loss. Her family history was significant for arthralgias and vertebral disc disorders in multiple family members, including both her children. Her mother carried a diagnosis of rheumatoid arthritis and osteoporosis. The only pertinent physical exam finding was short stature (Height -4’6”). A DEXA scan was performed using a Hologic unit and revealed a T Score of -1.0 at the L-spine and -1.9 at the femoral neck. A FRAX score predicted a 14% risk of major osteoporotic fracture and 4% risk of hip fracture.Laboratory data revealed: Serum Calcium 9.3 (8.5-10.5 mg/dL), Albumin 4.3 (3.5-5.0 g/dL), ALP 21 (<130 U/L), Vitamin D 25OH 46.2 (>30 ng/ml), Intact PTH 28.3 (15.0-65.0 pg/ml), Vitamin B6 87.7 (2-21 ng/ml).On review of her medical record, low ALP levels ranging between 20-30 U/L were noted to be present for the last twenty years. Given her history of musculoskeletal complaints, short stature, elevated Vitamin B6 and low ALP, genetic testing for hypophosphatasia was performed. Her results confirmed a known pathogenic mutation in the ALPL gene. Conclusion: This case highlights the importance of reviewing ALP levels and relevant patient history to rule out hypophosphatasia prior to initiating therapy for osteoporosis. This condition is often unrecognized. Bisphosphonates, which are often the first line of treatment in osteoporosis, are contraindicated in hypophosphatasia as they can increase the risk of atypical fractures.1 Teriparatide may improve bone density depending on the extent of ALP deficiency. Asfotase alfa is a new agent that is currently available for the management of certain cases of hypophosphatasia.

Role of Gamma Glutamyltransferase and Alkaline Phosphatase Assay in Enzymatic Panel for Hepatobiliary Function in Patients Attending Kibungo Hospital, Rwanda

Background: Liver complications show specific processes like hepatoxicity associated with drugs, primary neoplasm, or hepatotropic virus infections. Different markers based on laboratory testing help to diagnose and monitor liver related conditions. Mostly used tests are classed in a set known as hepatic panel or liver profile mainly consisting of body enzymes.Objective: The objective of the present study was to ascertain the role of gamma glutamyltransferase (GGT) and alkaline phosphatase (ALP) assay in enzymatic panel for hepatobiliary function assessment among patients attending Kibungo hospital.Methods: Two hundred twenty-five clients were included in the study. Demographic data were collected from December 2016 to March 2017. Blood sera were also collected and tested for serum GGT and ALP levels. Statistical package for social sciences (SPSS) was used in data analysis.Results: Seventy-four point seven per cent of clients had normal GGT whereas 63.1% had normal ALP. The 0.9% of clients comprised low levels of ALP. The means were 53 and 153 U/L for GGT and ALP, respectively. Fifty per cent of alcohol consumers’ population had elevated GGT and ALP. An increase of 69.2 and 61.5% for GGT and ALP, respectively was observed in smokers’ population. The subpopulation of hepatitis C virus (HCV) was the most with elevated GGT and ALP levels. In HIV population, serum GGT and ALP were raised at 31.1 and 37.8%, respectively. In fact, hepatitis B virus (HBV), HCV, and HIV patients are clinically considered as immuno-compromised people. Alcohol consumption and smoking were also found to increase GGT and ALP concentrations. In addition, GGT and ALP levels were simultaneously elevated in 19.6% of the clients, indicating the frequency of cholestatic liver disease.Conclusion: Elevated GGT and ALP revealed the occurrence of cholestasis among study participants due to factors that elevate serum GGT and ALP levels as a result of dysfunctional liver conditions. In hospital laboratories, GGT and ALP should always be included in the panel of tests for screening and bio-monitoring liver related conditions in Rwanda.

The role of apoptosis associated speck-like protein containing a caspase-1 recruitment domain (ASC) in response to bone substitutes.

The apoptosis-associated Speck-like protein containing a caspase-1 recruitment domain (ASC), present in inflammasomes, regulates inflammation events and is involved in osteogenic phenotype. Nevertheless, its function in bone repair induced by bone substitute biomaterials is unclear. This study aimed to unveil the role of ASC on osteoprogenitor and tissue response to stoichiometric-hydroxyapatite (HA), nanostructured carbonated-hydroxyapatite (CHA), and CHA containing 5% Strontium (SrCHA), characterized previously by XRD, uXRF-SR, and FTIR spectroscopy implants. Thereafter, conditioned media by the biomaterials were used later to treat pre-osteoblasts and an osteogenic stimulus was shown in response to the materials, with higher expression of Runx2, Osterix, ALP, and Collagen 1a1 genes, with significant involvement of inflammatory-related genes. Thus, to better address the involvement of inflammasome, primary cells obtained from both genotypes [Wild-Type (WT) and ASC Knockout (ASC-KO) mice] were subjected to conditioned media up to 7days, and our data reinforces both HA and CHA induces lower levels of alkaline phosphatase (ALP) than SrCHA, considering both genotypes (p<0.01), and ASC seems contribute with osteogenic stimulus promoted by SrCHA. Complimentarily, the biomaterials were implanted into both subcutaneous and bone defects in tibia. Histological analysis on 28days after implantation of biomaterials into mice's subcutaneous tissue revealed moderate inflammatory response to them. Both histomorphometry and μCT analysis of tibias indicated that the biomaterials did not reverse the delay in bone repair of ASC KO, reinforcing the involvement of ASC on bone regeneration and bone de novo deposition. Also, the bone density in CHA was >2-fold higher in WT than ASC-KO samples. HA was virtually not resorbed throughout the experimental periods, in opposition to CHA in the WT group. CHA reduced to half-area after 28days, and the bone deposition was higher in CHA for WT mice than HA. Taken together, our results show that biomaterials did not interfere with the healing pattern of the ASC KO, but CHA promoted higher bone deposition in the WT group, probably due to its greater biodegradability. These results reinforce the importance of ASC during bone de novo deposition and healing.

Can we identify individuals with an ALPL variant in adults with persistent hypophosphatasaemia?

BackgroundHypophosphatasia (HPP) is an inborn error of metabolism characterized by low levels of serum alkaline phosphatase (ALP). Scarce evidence exists about features that should signal the potential association between hypophosphatasaemia and HPP in adults. The aim of this study is to estimate the prevalence of ALPL variants in subjects with persistent hypophosphatasaemia and determine the associated clinical and laboratory features. For this cross-sectional study, laboratory records of 386,353 subjects were screened by measurement of ALP activity. A total of 85 (0.18%) subjects with persistent hypophosphatasaemia (≥2 serum alkaline phosphatase–ALP–measurements ≤35 IU/L and none > 45 IU/L) were included (secondary causes previously discarded). ALPL genetic testing and a systematized questionnaire to retrieve demographic, clinical and laboratory data were performed. Descriptive analysis and logistic regression models were employed to identify the clinical and laboratory characteristics associated with ALPL variants.ResultsForty subjects (47%) had a variant(s) in ALPL. With regard to clinical characteristics, the presence of an ALPL variant was significantly associated only with musculoskeletal pain (OR: 7.6; 95% IC: 1.9–30.9). Nevertheless, a trend to present more dental abnormalities (OR: 3.6; 95% IC: 0.9–13.4) was observed. Metatarsal stress fractures were also more frequent (4 vs 0; p < 0.05) in this group. Regarding laboratory features, median ALP levels were lower in subjects with ALPL variants (26 vs 29 IU/L; p < 0.005). Interestingly, the threshold of ALP levels < 25 IU/L showed a specificity, positive predictive value and positive likelihood ratio of 97.8, 94.4% and 19.8 to detect a positive ALPL test, respectively.ConclusionsIn subjects with persistent hypophosphatasaemia –secondary causes excluded– one out of two presented ALPL variants. Musculoskeletal pain and ALP levels < 25 IU/L are associated with this variant(s). In this scenario, ALP levels < 25 IU/L seem to be very useful to identify individuals with the presence of an ALPL variant.

Loss-of-Function Mutations in the ALPL Gene Presenting with Adult Onset Osteoporosis and Low Serum Concentrations of Total Alkaline Phosphatase.

ABSTRACTHypophosphatasia (HPP) is a rare inherited disorder characterized by rickets and low circulating concentrations of total alkaline phosphatase (ALP) caused by mutations in ALPL. Severe HPP presents in childhood but milder forms can present in adulthood. The prevalence and clinical features of adult HPP are poorly defined. The aim of this study was to evaluate the prevalence and clinical significance of low serum total alkaline phosphatase (ALP) levels in a clinic‐based population of adult osteoporotic patients. We searched for patients with low ALP in a cohort of 3285 patients referred to an osteoporosis clinic over a 10‐year period and performed mutation screening of ALPL in those with low ALP (≤40 U/L) on two or more occasions. These individuals were matched with four clinic controls with a normal ALP. We also evaluated the prevalence of low ALP and ALPL mutations in 639 individuals from the general population from the same region. We identified 16/3285 (0.49%) clinic patients with low ALP and 14 (87.5%) had potentially pathogenic variants in ALPL. Eight of these individuals were heterozygous for mutations previously described in HPP and 2 were heterozygous for novel mutations (p.Arg301Trp and p.Tyr101X). These mutations were not found in clinic controls or in the general population. Eight patients with low ALP, including 4 with ALPL mutations, were treated with bisphosphonates for an average of 6.5 years. In these individuals, the rate of fractures during treatment was comparable to that in normal ALP clinic controls who were treated with bisphosphonates. We conclude that heterozygous loss‐of‐function mutations in ALPL are common in osteoporosis patients with low ALP. Further studies are required to determine how best these individuals should be treated. © 2019 The Authors. Journal of Bone and Mineral Research published by American Society for Bone and Mineral Research.

Adult-Onset Hypophosphatasia: Before and After Treatment with Asfotase ALFA

To review the diagnosis and clinical course of a woman with hypophosphatasia who is being treated with newly approved enzyme replacement therapy, asfotase alfa. Clinical and laboratory data are presented. This is a unique report of a woman with debilitating adult-onset hypophosphatasia who was successfully diagnosed with low alkaline phosphatase (ALP) levels and elevated vitamin B6 levels. Treatment with asfotase alfa resolved her chronic bony pain symptoms and quadrupled her daily pedometer step count. Furthermore, whole body scans before and after treatment showed less focal uptake overall, suggesting fracture healing after enzyme replacement therapy. Improvement in patient reported symptoms, daily pedometer count, and whole body scans was noted after treatment of adult-onset hypophosphatasia with asfotase alfa enzyme replacement therapy. The significance of increased ALP levels after treatment is currently unknown.

Osteocalcin is an Independent Predictor for Hungry Bone Syndrome After Parathyroidectomy.

Hungry bone syndrome is characterized by prolonged and severe hypocalcemia following parathyroidectomy. Previously, we reported that preoperative alkaline phosphatase is a major factor predicting prolonged hospital stay. Nonetheless, some patients with low alkaline phosphatase levels presented with hungry bone syndrome, suggesting that additional factors may play a role. From September 2010 to December 2017, consecutive dialysis patients who underwent parathyroidectomy for secondary hyperparathyroidism were analyzed. Length of hospital stay was used as a surrogate marker for postoperative bone hunger. A total of 260 patients were included in the study. The median postoperative hospital stay was 3days, and 69 (27%) patients had a stay longer than 3days. Multivariate logistic regression analysis revealed that alkaline phosphatase (odds ratio [OR] = 1.005), osteocalcin (OR = 1.001), and subtotal parathyroidectomy (OR = 0.061) were associated with prolonged hospital stay. Multivariate linear regression analysis indicated that age (β = - 0.170), alkaline phosphatase (β = 0.430), and osteocalcin (β = 0.166) were correlated with the length of stay. After surgery, the median osteocalcin level increased from 264 to 478ng/mL (P < 0.001). Alkaline phosphatase is the main predictor of hungry bone syndrome after parathyroidectomy, and preoperative osteocalcin is an additional independent predictor. Patients with a high osteocalcin level may prone to have a higher demand for calcium supplementation.

Epidemiological, Clinical and Genetic Study of Hypophosphatasia in A Spanish Population: Identification of Two Novel Mutations in The Alpl Gene

Hypophosphatasia (HPP) is a genetic disease caused by one or several mutations in ALPL gene encoding the tissue-nonspecific alkaline phosphatase affecting the mineralization process. Due to its low prevalence and lack of recognition, this metabolic disorder is generally confused with other more frequent bone disorders. An assessment of serum total alkaline phosphatase (ALP) levels was performed in 78,590 subjects. Pyridoxal-5′-phosphate (PLP) concentrations were determined and ALPL gene was sequenced in patients potentially affected by HPP. Functional validation of the novel mutations found was performed using a cell-based assay. Our results showed persistently low serum ALP levels in 0.12% of subjects. Among the studied subjects, 40% presented with HPP-related symptoms. Nine of them (~28%) had a history of fractures, 5 (~16%) subjects showed chondrocalcinosis and 4 (~13%) subjects presented with dental abnormalities. Eleven subjects showed increased PLP concentrations. Seven of them showed ALPL gene mutations (2 of the mutations corresponded to novel genetic variants). In summary, we identified two novel ALPL gene mutations associated with adult HPP. Using this protocol, almost half of the studied patients were diagnosed with HPP. Based on these results, the estimated prevalence of mild HPP in Spain could be up to double than previously reported.

Surgical outcomes and prognostic factors for patients with gastric cancer spinal metastasis.

PurposeTo investigate the outcome and prognostic factors of surgery in treating gastric cancer spinal metastasis (GCSM).Patients and methodsA total of 17 patients with GCSM who have undertaken spinal surgeries have been identified. Kaplan–Meier method and univariate analysis are adopted to investigate the prognostic factors affecting overall survival (OS) and progression-free survival (PFS).ResultsThe median PFS and OS are 11.3 months (95% CI: 7.8–14.9 months) and 11.9 months (95% CI: 8.4–15.4 months), respectively. Postoperatively, all patients had substantial pain relief, with mean visual analog scale score descending from 6.6±1.6 to 3.4±1.2. Meanwhile, patients also showed improved neurological functions, with 8 of them having improvements of at least one level in Frankel classification. Univariate analysis presented that patients with carcinoembryonic antigen (CEA)<6 µg/L (p=0.020), lactate dehydrogenase (LDH)<300 U/L (p=0.012), alkaline phosphatase (ALP)<200 U/L (p=0.007), and Tokuhashi score>6 (p=0.027) show longer OS. Moreover, application of bone cement, low level of ALP (<200 U/L), and LDH (<300 U/L) are associated with longer PFS (p<0.05).ConclusionsSurgery is an efficient option in treating GCSM, due to its efficacy in pain alleviation, function restoration, and stability reconstruction. Low levels of CEA, LDH, ALP, and high Tokuhashi score (>6) are all favorable factors for better OS, whereas low levels of LDH, ALP, and application of bone cement are related with longer PFS.

Single and simultaneous effects of acrylamide and ethanol on bone microstructure of mice after one remodeling cycle

BackgroundThis study aimed to examine femoral bone microstructure of mice after single and simultaneous administration to acrylamide and ethanol since both substances are often consumed separately and/or together by humans. Interactive effects of these toxins were analysed after one remodeling cycle.MethodsTwenty clinically healthy adult mice were randomly divided into four groups following 2 weeks administration of toxins: A group - mice were fed with acrylamide (40 mg/kg bw); E group - mice were ethanol-fed (15% ethanol); AE group - mice were simultaneously fed with both toxins, and a C group – control (without acrylamide and/or ethanol supplementation). Generally, 2D and 3D imaging methods were used to determine cortical and trabecular bone tissues microstructure. Biochemical analyses of plasma parameters were also realized using commercially available ELISA tests and spectrophotometrically.ResultsSingle and simultaneous exposure to acrylamide and ethanol affected only cortical bone microstructure. No significant changes in trabecular bone morphometry were detected among all groups. In mice from the A group, increased endocortical remodeling associated with a higher level of serum calcium and vasoconstriction of primary osteon’s vascular canals (POVC) were identified. On the contrary, increased cortical porosity consistent with a decreased relative bone volume, bone mineral density (BMD) and lower levels of alkaline phosphatase (ALP), glutathione (GSH), calcium in plasma and also with vasodilation of POVC were observed in the E group. In the AE group, the highest density of secondary osteons associated with a lower BMD and decreased levels of ALP, GSH were documented. The parameters of POVC and Haversian canals approximated to the C group. In addition, single and simultaneous exposure to both toxins caused liver disease consistent with a higher values of alanine aminotransferase (ALT), aspartate aminotransferase (AST) in plasma of all experimental groups.ConclusionsSingle administration to acrylamide and ethanol had negative effects on cortical bone structure of mice after one remodeling cycle. However, we identified possible antagonistic impact of these toxins on the structure of the cortical bone.

SUN-LB051 Low Alkaline Phosphatase? Rule out Growth Hormone Deficiency.

Background: In a child with low alkaline phosphatase (ALP), the current algorithms include screening for genetic hypophosphatasia, nutritional deficiencies, vitamin D excess, hypoparathyroidism, celiac disease, and Wilson’s disease(1). Growth hormone deficiency is not often listed in the differential diagnoses. Growth hormone is critical for longitudinal bone growth. ALP is a known marker of bone formation. Clinical Case: A 9-year-old girl with ADHD, gastroesophageal reflux, and chronic constipation presented to the endocrinology clinic for failure to thrive (weight 26thpercentile, height 11th percentile). Other symptoms included easy bruising, non-specific bone pain, and delayed loss of deciduous teeth. Adoptive parents reported recent stagnation of height and weight. Initial laboratory work-up was normal except low ALP level of 77U/L (range 184-415), low IGF 1 of 74ng/mL (-2.2 SD), and normal IGF BP3 level of 3.1 mg/dL (range 1.8-7.1). Bone age was not delayed. Repeat ALP level 4 and 5 months later was 70-80 U/L with an elevated vitamin B6 level of 102ug/dL (range 2-32.8; 1 week after discontinuation of multivitamin), which was suspicious for hypophosphatasia. Skeletal survey was non-concerning. Other screening labs including urine phosphoethanolamine, serum zinc, magnesium, and vitamin D levels were normal. On repeat clinical evaluation five months later, the patient's height and weight had plateaued. Dual-agent growth hormone stimulation testing revealed a peak growth hormone level of 7.73 ng/mL (cut-off 10ng/mL), which was strongly suggestive of growth hormone deficiency. The patient was started on recombinant growth hormone (rGH) therapy at 0.3 mg/kg/week. Two months later, ALP level increased to 205 U/L with a vitamin B6 level of 86 ug/L. ALP has remained normal for age 6 months after starting rGH therapy, with a growth velocity of 9 cm per year, and improved vitamin B6 level. Bone pains have resolved. The patient was seen by the department of genetics recently, and confirmed to not have any mutation in the ALPL gene. Conclusions: 1) A low alkaline phosphatase level in a child with short stature can be an indicator of growth hormone deficiency. 2) ALP levels improve with replacement of growth hormone and increase in growth velocity. Reference: (1) Saraff V, Högler W et al, A Diagnostic Algorithm for Children with Low Alkaline Phosphatase: Lessons Learned from Laboratory Screening for Hypophosphatasia, The Journal of Pediatrics, Vol 172, 2016, Pg 181-186 Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. s presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.

MON-495 Hypophosphatasia: A Rare Cause of Osteoporosis in a Young Adult Male

Introduction: Secondary osteoporosis is due to an identifiable cause of osteoporosis. Hypophosphatasia is a rare cause of secondary osteoporosis and needs to be considered when evaluating osteoporosis in young people. We present a case of secondary osteoporosis initially thought to be a result of malabsorptive disorder and chronic steroid use, with eventual diagnosis of autosomal dominant hypophosphatasia as the primary underlying cause. Clinical Case: A 24 year old male who was seen for evaluation of osteoporosis. He reported an extensive history of fractures about 26 in total, including wrist, shoulders, nose, and metatarsals. Past history was also significant for bowed legs at birth requiring osteotomies and spontaneous loss of several teeth with root intact, requiring extractions. He was also diagnosed with Crohn’s disease at 17 years old and history of steroid use, however was not on steroids at time of initial evaluation. He was diagnosed with bilateral avascular necrosis at age 18 years and needed bilateral hip replacement at age 20 years. There was no family history of skeletal disorders. DEXA scan obtained for the assessment of bone density revealed a Z score of -2.6 in the lumbar spine and -2.1 in the distal forearm. Further evaluation for secondary causes of osteoporosis revealed a normal TSH, PTH, tryptase, vitamin D and testosterone levels. Bone turnover markers were normal except for a low alkaline phosphatase. It was noted that the patient had a persistently low alkaline phosphatase for the last 6 years despite his frequent fractures. Hypophosphatasia was suspected given the history and the low alkaline phosphatase levels. Pyridoxal 5-phosphate was elevated at 77mcg/L (normal 5-50mcg/L). Genetics evaluation revealed a heterozygous, missense mutation in ALPL gene, confirming diagnosis of autosomal dominant hypophosphatasia. He was started on enzyme replacement therapy with asfotase alpha. Conclusion: Hypophosphatasia is a rare metabolic bone disease due to a deficiency of alkaline phosphatase which may present from infancy to adulthood. Diagnosis is made by finding a low alkaline phosphatase level and elevated 5 pyridoxal phosphate. Enzyme replacement therapy with asfotase alpha is the mainstay of treatment. It is probably underdiagnosed secondary to its rarity and therefore must be considered in any young patient who presents with osteoporosis.

MON-497 Adult Onset Hypophosphatasia: Before and After Treatment with Asfotase Alfa

Hypophosphatasia is a rare inherited bone disease resulting from mutations in the gene encoding tissue-nonspecific alkaline phosphatase (TNSALP), an enzyme predominant in skeleton, liver, kidney and teeth. Diminished TNSALP activity causes accumulation of substrates that inhibit bone mineralization resulting in debilitating pain, fractures and low alkaline phosphatase (ALP) levels. In 2015 the FDA approved asfotase alfa, a bone-targeted recombinant TNSALP used for enzyme replacement therapy. We present a case of hypophosphatasia treated with asfotase alfa resulting in improvements in whole body scan and pedometer step counts. In 2014, a 52-year-old female with chronic pain presented with over 30 years of bony pain, poor balance, falls, fractures and life-long dental disease. Physical exam displayed tenderness of long bones and waddling gait. Blood work was remarkable for low ALP at 11 U/L (normal 35-120 U/L) and low bone-specific ALP of 3 ug/L (normal 7.0-22.4 ug/L). Vitamin B6 level was >2000 nmol/L (normal 20.0-125.0 nmol/L). Calcium level was 9.8 mg/dL (normal 8.5-10.1 mg/dL). Serum phosphorus was elevated at 5.2 mg/dL (normal 2.3-4.6 mg/dL). Intact parathyroid hormone level was elevated at 114.1 pg/mL (normal 18.5-88.0 pg/mL), with known diagnosis of chronic kidney disease, GFR 27 mL/min. Her 24-hour urine calcium, serum protein electrophoresis, celiac test, thyroid studies and vitamin D level were normal. N-telopeptide was elevated at 25.9 nM (normal 6.2 to 19.0 nM). SPECT whole body scan demonstrated increased uptake with multiple fractures of the axial skeleton and proximal femurs; consistent with oncogenic osteomalacia. Fibroblast growth factor 23 and indium 111 octreotide scan showed no evidence of malignancy. DEXA scan showed osteopenia of the hip and forearm. She was diagnosed with adult-onset hypophosphatasia. Initially, due to lack of options, she was treated with denosumab. After three injections, she developed a new atypical femur fracture requiring surgical rod placement; denosumab was discontinued. In 2017, she was started on asfotase alfa with significant improvements in balance, endurance, and bone pain. Prior to treatment, the patient required narcotic oral pain medicine, fentanyl patch and an assistive device to walk 3000 steps daily; after treatment, she is walking over 10,000 steps daily without any pain pharmacotherapy. Repeat whole body scan showed less focal uptake overall, consistent with healing fractures. This case highlights clinical proof of improvement after treatment with asfotase alfa based on increased daily step count and healing fractures on whole body scans. Asfotase alfa is a newly approved therapy for hypophosphatasia and therefore long-term outcomes are not yet available, however short term patient reported subjective findings and clinical data are reassuring for successful treatment.

Ectopic Ocular Surface Calcification in Patients With Hypophosphatasia Treated With Asfotase Alfa

To assess for ectopic ocular calcification in a series of patients with hypophosphatasia (HPP) treated with asfotase alfa, a recombinant tissue-nonspecific alkaline phosphatase. This is a retrospective analysis of subjects enrolled at Duke University Medical Center in ENB-009-10 (ClinicalTrials.gov: NCT01163149), a randomized controlled trial of asfotase alfa in adolescents and adults with HPP. Seven patients between the ages of 45 and 66 years diagnosed with HPP based on clinical features and low serum alkaline phosphatase levels were enrolled at our site. Subjects were randomized to receive either daily subcutaneous injections of asfotase alfa or no treatment. After 24 weeks, during the open-label extension phase, all subjects received treatment for at least 4 years. All subjects underwent comprehensive eye examinations at baseline and at 24-week intervals throughout the study to assess for development of ocular calcifications. By week 120, all 7 subjects developed asymptomatic white refractile deposits in the interpalpebral perilimbal conjunctiva. Biopsy of the conjunctival lesions in 2 subjects revealed elastosis with subepithelial calcification. The lesions were nonprogressive and in 5 subjects exhibited some degree of regression. Asfotase alfa was invariably associated with development of mild focal conjunctival calcification, likely through disinhibition of hydroxyapatite crystal propagation. The calcifications were not symptomatic or vision-threatening and should not preclude enzyme replacement therapy for patients with this rare and often debilitating disease.

Genotype-phenotype relationship in a large cohort of osteogenesis imperfecta patients with COL1A1 mutations revealed by a new scoring system.

Background:Osteogenesis imperfecta (OI), a heritable bone fragility disorder, is mainly caused by mutations in COL1A1 gene encoding α1 chain of type I collagen. This study aimed to investigate the COL1A1 mutation spectrum and quantitatively assess the genotype-phenotype relationship in a large cohort of Chinese patients with OI.Methods:A total of 161 patients who were diagnosed as OI in Department of Endocrinology of Peking Union Medical College Hospital from January 2010 to December 2017 were included in the study. The COL1A1 mutation spectrum was identified by next generation sequencing and confirmed by Sanger sequencing. A new clinical scoring system was developed to quantitatively assess the clinical severity of OI and the genotype-phenotype relationship was analyzed. The independent sample t-test, analysis of variance, Mann-Whitney U-test, Chi-squared test, Pearson correlation, and multiple linear regression were applied for statistical analyses.Results:Among 161 patients with OI, 32.9% missense mutations, 16.8% non-sense mutations, 24.2% splice-site mutations, 24.8% frameshift mutations, and 1.2% whole-gene deletions were identified, of which 38 variations were novel. These mutations led to 53 patients carrying qualitative defects and 67 patients carrying quantitative defects in type I collagen. Compared to patients with quantitative mutations, patients with qualitative mutations had lower alkaline phosphatase level (296 [132, 346] U/L vs. 218 [136, 284] U/L, P = 0.009) and higher clinical score (12.2 ± 5.3 vs. 7.4 ± 2.4, P < 0.001), denoting more severe phenotypes including shorter stature, lower bone mineral density, higher fracture frequency, more bone deformity, vertebral compressive fractures, limited movement, and dentinogenesis imperfecta (DI). Patients would not present with DI if the glycine substitutions happened before the 79th amino acid in triple helix of α1 chains.Conclusions:This presented distinctive COL1A1 mutation spectrum in a large cohort of Chinese patients with OI. This new quantitative analysis of genotype-phenotype correlation would be helpful to predict the prognosis of OI and genetic counseling.

Alkaline phosphatase is a predictor of Bone Mineral Density in postmenopausal females.

Objectives:The study was planned to determine whether serum calcium, phosphate and alkaline phosphatase (ALP) are predictors of bone mineral density (BMD) in postmenopausal non-osteoporotic, osteopenic, and osteoporotic females.Methods:In this cross sectional study, conducted at Shaikh Zayed Hospital, Lahore in the year 2014-2015, postmenopausal females between 50-70 years of age were taken and divided into three groups non-osteoporotic (n=52), osteopenic (n=69) and osteoporotic (n=47). Serum ALP, phosphate and calcium were used in a stepwise multiple regression analysis to predict T-score in these groups.Results:In normal postmenopausal females, the prediction model was statistically significant, F(2, 41) = 6.041, p < 0.05 and showed a T-score variance of 22%. T-score was primarily predicted by higher levels of phosphate and calcium. In postmenopausal osteopenic females, T-score was only predicted by lower levels of ALP. The model was statistically significant, F(1, 59) = 4.995, p < 0.05, and accounted for approximately 7% of the variance of T-score. In postmenopausal osteoporotic females, the prediction model contained no predictors.Conclusion:Our study suggested that calcium and phosphate are the strongest predictors of T-score in postmenopausal normal females, while in postmenopausal osteopenic females ALP was the strongest predictor of T-score. Elevated serum ALP levels may help in determining loss of BMD in postmenopausal females.

Hypophosphatasia in Adults: Clinical Spectrum and Its Association With Genetics and Metabolic Substrates

Background: Hypophosphatasia (HPP) is a rare metabolic bone disorder caused by mutations in the alkaline phosphatase (ALPL) gene, and characterized by low circulating alkaline phosphatase (ALP) levels and bone, muscle, dental and systemic manifestations. In this case series we investigate the clinical spectrum, genetic and biochemical profile of adult HPP patients from the University Hospitals Leuven, Belgium. Methodology: Adults with HPP were identified through medical record review. Inclusion criteria were: (1) age ≥ 16 yr; (2) consecutively low ALP levels not explained by secondary causes; (3) one or more of the following supporting criteria: biochemical evidence of elevated enzyme substrates; subtrochanteric fractures, metatarsal fractures or other typical clinical features; family history of HPP; a known or likely pathogenic ALPL mutation. Results: Nineteen patients met our inclusion criteria (n = 2 infantile, n = 6 childhood, n = 10 adult-onset HPP and one asymptomatic carrier). Fractures and dental abnormalities were the most reported symptoms. Fatigue was reported in n = 7/19 patients (37%), three of which had previously been misdiagnosed as having chronic fatigue syndrome and/or fibromyalgia. Empirical pyridoxine therapy in four patients (without seizures) did not provide symptomatic relief. N = 7/19 patients (37%) were inappropriately treated or planned to be treated with antiresorptive treatment. Two patients developed atypical femoral fractures following exposure to bisphosphonates and/or denosumab. Patients detected by screening were less severely affected, while patients with homozygous or compound heterozygous mutations had the most severe symptoms, significantly lower circulating ALP levels (p = 0.013) and significantly higher pyridoxal-5’-phosphate (p = 0.0018) and urinary phosphoethanolamine (p = 0.0001) concentrations. Conclusions: Screening may detect mainly less severely affected individuals, which may nevertheless avoid misdiagnosis and inappropriate antiresorptive drug exposure. Patients with biallelic mutations had more severe symptoms, significantly lower ALP and higher substrate levels. Whether the latter finding has implications for the classification and treatment of HPP should be investigated further in larger cohorts.

Effects of polymethylmethacrylate nanoplastics on Dicentrarchus labrax

The present study aimed to evaluate the effects of ~45 nm nanoplastics (NPs) on the marine fish Dicentrarchus labrax after a short-term exposure. Animals were exposed to a concentration range of NPs for 96 h and liver, plasma and skin mucus were sampled. Assessed endpoints included biochemical biomarkers and expression of genes related to lipid metabolism, immune system and general cell stress. Abundance of mRNA transcripts related to lipid metabolism, pparα and pparγ, were significantly increased after exposure to NPs. Biochemical endpoints revealed decreased esterase activity levels in plasma, suggesting that the immune system of fish might be compromised by exposure to NPs. Moreover, significantly lower levels of alkaline phosphatase were found in the skin mucus of animals exposed to NPs. The present results suggest that NPs may represent a hazard to this marine fish, potentially interfering with the metabolism of lipids and the correct function of the immune response.

Abnormal bone turnover in individuals with low serum alkaline phosphatase.

The clinical spectrum of hypophosphatasia (HPP) is broad and variable within families. Along severe infantile forms, adult forms with mild manifestations may be incidentally discovered by the presence of low alkaline phosphatase (ALP) activity in serum. However, it is still unclear whether individuals with persistently low levels of ALP, in the absence of overt manifestations of HPP, have subclinical abnormalities of bone remodeling or bone mass. The aim of this study was to obtain a better understanding of the skeletal phenotype of adults with low ALP by analyzing bone mineral density (BMD), bone microarchitecture (trabecular bone score, TBS), and bone turnover markers (P1NP and ß-crosslaps). We studied 42 individuals with persistently low serum ALP. They showed lower levels of P1NP (31.4 ± 13.7 versus 48.9 ± 24.4ng/ml; p = 0.0002) and ß-crosslaps (0.21 ± 0.17 versus 0.34 ± 0.22ng/ml, p = 0.0015) than individuals in the control group. There were no significant differences in BMD, bone mineral content, or TBS. These data suggest that individuals with hypophosphatasemia have an overall reduction of bone turnover, even in the absence of overt manifestations of HPP or low BMD. We evaluated bone mineral density (BMD), bone microarchitecture, and bone turnover markers in patients with low serum levels of alkaline phosphatase. Our results show that these patients have low bone remodeling even in the absence of BMD abnormalities, thus supporting the recommendation of avoiding antiresorptives such as bisphosphonates in these subjects.