Intermittent Hypercalcemia Research Articles

8082 Primary Hyperparathyroidism or Familial Hypocalciuric Hypercalcemia? Why Not Both?

Abstract Disclosure: C.A. Zmijewski: None. P.D. Greenberg: None. S.R. Saul: None. Background: Although considered two separate entities, primary hyperparathyroidism (PHPT) and familial hypocalciuric hypercalcemia (FHH) can present concurrently. Case: A 68-year-old male with hypertension was referred to Endocrinology for hypercalcemia and osteoporosis. The patient reported a long-standing history of intermittent hypercalcemia, first diagnosed at age 30 with a strong family history, both his father and son. He denied symptoms of hypercalcemia, history of nephrolithiasis and fractures, and was not taking calcium supplementations. Labs were notable for intermittent elevations in calcium, the highest being 10.9 mg/dL (8.5-10.5 mg/dL), in addition to phosphorus levels as low as 1.7 mg/dL (2.5-4.5 mg/dL). Vitamin D was replete at 50 ng/mL (32-100 ng/mL) and the highest parathyroid hormone (PTH) was 124 pg/mL (10-66 pg/mL). The 24-hour urine for calcium was 117 mg (100-300 mg) with a Ca/Cr 0.01. DEXA scan showed T scores -2.2 at the right femoral neck and -3.4 at the distal radius (Z score -2.3). Due to the significant osteoporosis, a work-up for secondary causes was completed and was unremarkable. The differential diagnosis for the osteoporosis, elevated parathyroid hormone, and intermittent hypercalcemia included PHPT vs FHH or possibly, a combination. Additional imaging included a renal ultrasound which was negative for nephrolithiasis, Sestamibi and 4D-CT which were both negative for a parathyroid adenoma. Genetic testing confirmed a mutation in the CASR gene. Due to the inability to localize a possible lesion, the decision was made to treat the osteoporosis with zoledronic acid. Conclusion: PHPT is a common endocrine disorder; approximately 100,000 people in the United States develop PHPT annually. Conversely, FHH is a rare endocrine disorder with an incidence rate of 1 in 78,000. PHPT occurs due to the over-secretion of PTH by one or more parathyroid glands. FHH is an inherited autosomal dominant disorder, most commonly due to an inactivating mutation in the calcium-sensing receptor (CASR) gene. Distinguishing PHPT from FHH is important because PHPT is cured with surgery while FHH does not require treatment. Hypercalcemia from FHH, as opposed to PHPT, is suggested by the absence of symptoms, a positive family history, normal or high PTH, and hypocalciuria. However, it can be challenging to separate the two especially in atypical presentations (PTH can be normal in PHPT and elevated in FHH, and Ca/Cr can be < 0.01 in PHPT). But what if these two conditions were to co-exist? Case reports have described patients with concurrent PHPT and FHH (parathyroid adenoma confirmed with pathology and CASR gene mutation confirmed with genetic testing). In these cases, parathyroidectomy can still be considered in co-existing PHPT and FHH to alleviate symptoms and prevent complications of hypercalcemia. Though a rare occurrence, PHPT and FHH have been shown to co-exist in prior case reports. Presentation: 6/1/2024

Normocalcaemic hyperparathyroidism and primary hyperparathyroidism: least significant change for adjusted serum calcium.

IntroductionThe least significant change (LSC) is a term used in individuals in order to evaluate whether one measurement has changed significantly from the previous one. It is widely used when assessing bone mineral density (BMD) scans. To the best of our knowledge, there no such estimate available in the literature for patients with disorders of calcium metabolism. Our aim was to provide an estimate of the least significant change for albumin-adjusted calcium in patients with normocalcaemic hyperparathyroidism (NPHPT) and primary hyperparathyroidism (PHPT).MethodsWe used the within-subject standard deviatio calculated in a population of NPHPT and PHPT patients and multiplied it by 2.77.ResultsThe LSC for NPHPT and PHPT were found to be 0.25 and 0.24 mmol/L, respectively (1.00 and 0.96 mg/dL). In clinical practice, the value of 0.25 mmol/L could be used.DiscussionThe least significant change given, could be used in two ways in these patients. First, it gives a range to which values are expected. This can provide some reassurance for the patient and the physician in cases of intermittent hypercalcaemia. Moreover, it can be a marker of whether an individual has an actual significant change of his calcium after parathyroid surgery.

Normocalcaemic primary hyperparathyroidism: An update on diagnostic and management challenges.

Normocalcaemic primary hyperparathyroidism is a condition that can present with intermittent hypercalcemia or may evolve into hypercalcemic primary hyperparathyroidism. This milder biochemical entity remains incompletely understood because of a lack of long-term health outcomes regarding both medical and surgical approaches to its management. Medical therapies have shown some efficacy. A limited number of studies have found that bisphosphonates increase bone mineral density, and calcimimetics may decrease the risk of nephrolithiasis in patients with normocalcaemic primary hyperparathyroidism. Studies have also described patient outcomes after applying the same surgical criteria used for patients with hypercalcaemic primary hyperparathyroidism to those with the normocalcaemic form of the disease. These studies suggest that parathyroid surgery appears to be effective in normalizing elevated serum parathyroid hormone concentrations and decreasing adverse renal and skeletal outcomes in patients with normocalcaemic hyperparathyroidism. Given the available data and overall lack of consensus regarding the optimal management of these patients, a reasonable approach is to tailor treatment to the individual patient by considering their risk factors for new or accelerated bone loss, kidney stones, diminished quality of life, and cardiovascular disease.

Variable Phenotypes Seen with a Homozygous CYP24A1 Mutation: Case Report

Vitamin D–mediated hypercalcemia may be due to benign or malignant conditions. Recently, loss-of-function mutations in the gene CYP24A1, which encodes 25-hydroxyvitamin D3-24-hydroxylase, have been described which result in reduced degradation of the active 1,25-(OH)2 D3, causing hypercalcemia and hypercalciuria. We describe four patients in whom we identified a novel CYP24A1 homozygous germline mutation (NM_000782.4: c.323A>G; p.(His108Arg). Three of the four patients had a long history of recurrent renal stones. One patient had nephrocalcinosis with significant renal impairment. The other three patients had intermittent hypercalcemia, which in two female patients predominantly occurred during pregnancy with severe gestational hypercalcemia. Germline CYP24A1 mutations are a rare but important cause of vitamin D–mediated hypercalcemia and demonstrate a core phenotype of renal stones, hypercalciuria, and PTH-independent hypercalcemia. However, even in the setting of a homozygous CYP24A1 germline mutation, hypercalcemia may be intermittent with a normal PTH level during the periods of normocalcemia resulting in the need for a high degree of clinical suspicion. Measurement of vitamin D metabolites, in particular the 25-(OH)D3/24,25-(OH)2D3 ratio which is elevated in patients with homozygous CYP24A1 germline mutations, may help provide a clue as to the underlying diagnosis. In women with a history of recurrent calcium-containing renal stones or nephrocalcinosis, we would recommend measurement of serum calcium levels prior to conception and each trimester due to the potential for severe adverse effects on mother and baby if an unidentified CYP24A1 mutation is present.

MON-925 A Wolf in Sheep’s Clothing: Intermittent Hypercalcemia from an Intrathyroidal Parathyroid Carcinoma

Parathyroid carcinomas have an estimated prevalence of <0.1% of all cancers and is found in <1% of patients with primary hyperparathyroidism (PHPT). While they frequently present with PTH- mediated hypercalcemia, they are often distinguished by severe hypercalcemia and markedly elevated PTH levels compared to their benign counterparts. Parathyroid cancers most often arise from existing parathyroid glands, making them identifiable with standard imaging modalities such as parathyroid sestamibi scan, thyroid ultrasound, and 4-D CT scan. There are reports of non-functioning parathyroid carcinomas, including those that are intrathyroidal. Most of the reported cases are found de novo. We present a case of an intrathyroidal parathyroid carcinoma with intermittent hypercalcemia. A 72-year-old man with a history of Graves’ disease and RAI ablation in the 1970’s was found to have hypercalcemia up to 14.1 mg/dL (8.5 - 10.1) with a PTH level of 223 pg/mL (14 - 64). He denied any constipation, bone pain, fractures, renal stones, or changes in mental status. Thyroid ultrasound demonstrated a 3.9 cm R lobe complex nodule reported as TI-RADS 4, and a hypoechoic 1.0 cm nodule in the L lobe. No definitive parathyroid adenoma was reported. A parathyroid sestamibi scan showed persistent uptake in area of the L 1.0 cm nodule favoring a PTH adenoma while the R nodule had initial radiotracer uptake with delayed washout but no technetium uptake. Laboratory evaluation demonstrated a 24-hour urinary calcium of 338 mg/24hr, low 25-OH vitamin D, and normal vitamin D 1,25 levels. Osteoporosis was diagnosed by BMD with T-score of -3.2 at the femoral neck. Repeat serum corrected calcium level was 9.7 mg/dL and PTH was 93 pg/mL. FNA cytology of the R thyroid mass was reported as benign thyroid tissue. Due to size of the R thyroid nodule, the patient underwent a R hemithyroidectomy with L parathyroidectomy. Intraoperative PTH levels decreased from 154 to 120 pg/mL after removal of L parathyroid adenoma; PTH level decreased further to 12.9 pg/mL after R hemithyroidectomy. Surgical pathology revealed 4.5 cm R parathyroid carcinoma without thyroid tissue with positive margins, and a hypercellular L parathyroid gland. PHPT resolved. After review of all aspects of the case and discussion with patient, the decision was made to monitor his calcium and PTH levels and repeat BMD 1 year from resection. This is an uncommon presentation of a rare endocrine malignancy. To our knowledge, there are few case reports of non-functional parathyroid carcinomas that were initially reported as thyroid cancer or benign thyroid tissue after biopsy. This report underscores the importance in keeping this rare diagnosis in the evaluation of PTH-mediated hypercalcemia.

Biallelic CYP24A1 variants presenting during pregnancy: clinical and biochemical phenotypes.

IntroductionInactivating mutations in CYP24A1, encoding vitamin D-24-hydroxylase, can lead to an accumulation of active vitamin D metabolites and consequent hypercalcaemia. Patient (infantile and adult) presentation is varied and includes mild-severe hypercalcaemia, hypercalciuria, nephrocalcinosis and nephrolithiasis. This study aimed to characterize the clinical and biochemical phenotypes of a family with two CYP24A1 missense variants.MethodsThe proband and seven family members underwent detailed clinical and biochemical evaluation. Laboratory measurements included serum calcium, intact parathyroid hormone (iPTH), vitamin D metabolites and urine calcium and creatinine.ResultsThe proband presented during the second trimester of a planned pregnancy with flu-like symptoms. Laboratory tests showed elevated adjusted calcium of 3.27 (upper reference limit (URL: 2.30) mmol/L), suppressed iPTH (<6 ng/L), elevated 25(OH)D (264 (URL: 55) nmol/L) and elevated 1,25(OH)D (293 (URL: <280) pmol/L). Ionized calcium was 1.55 (URL: 1.28) mmol/L. Sanger sequencing revealed two heterozygous missense variants in the CYP24A1: p.(Arg439Cys), R439C and p.(Trp275Arg), W275R. The proband’s brother and sister had the same genotype. The brother had intermittent hypercalcaemia and hypervitaminosis D. Only the sister had a history of nephrolithiasis. The proband’s daughter and two nephews were heterozygous for the R439C variant. The proband and her brother frequently had elevated 25(OH)D:24,25(OH)2D ratios (>50) during follow-up.ConclusionsW275R is a new pathogenic CYP24A1 mutation in compound heterozygotic form with R439C in this family.

Phosphate matters when investigating hypercalcemia: a mutation in SLC34A3 causing HHRH

SummaryHereditary hypophosphatemic rickets with hypercalciuria (HHRH) is a rare, autosomal recessive disorder caused by mutations in the SLC34A3 gene that encodes the renal sodium-dependent phosphate cotransporter 2c (NaPi-IIc). It may present as intermittent mild hypercalcemia which may attract initial diagnostic attention but appreciation of concomitant hypophosphatemia is critical for consideration of the necessary diagnostic approach. A 21-year-old woman was assessed by adult endocrinology for low bone mass. She initially presented age two with short stature, nephrocalcinosis and mild intermittent hypercalcemia with hypercalciuria. She had no evidence of medullary sponge kidney or Fanconi syndrome and no bone deformities, pain or fractures. She had recurrent episodes of nephrolithiasis. In childhood, she was treated with hydrochlorothiazide to reduce urinary calcium. Upon review of prior investigations, she had persistent hypophosphatemia with phosphaturia, low PTH and a high-normal calcitriol. A diagnosis of HHRH was suspected and genetic testing confirmed a homozygous c.1483G>A (p.G495R) missense mutation of the SLC34A3 gene. She was started on oral phosphate replacement which normalized her serum phosphate, serum calcium and urine calcium levels over the subsequent 5 years. HHRH is an autosomal recessive condition that causes decreased renal reabsorption of phosphate, leading to hyperphosphaturia, hypophosphatemia and PTH-independent hypercalcemia due to the physiologic increase in calcitriol which also promotes hypercalciuria. Classically, patients present in childhood with bone pain, vitamin D-independent rickets and growth delay. This case of a SLC34A3 mutation illustrates the importance of investigating chronic hypophosphatemia even in the presence of other more common electrolyte abnormalities.Learning points:Hypophosphatemia is an important diagnostic clue that should not be ignored, even in the face of more common electrolyte disorders.HHRH is a cause of PTH-independent hypophosphatemia that may also show hypercalcemia.HHRH is a cause of hypophosphatemic nephrocalcinosis that should not be treated with calcitriol, unlike other congenital phosphate wasting syndromes.Some congenital phosphate wasting disorders may not present until adolescence or early adulthood.

Loss-of-Function Mutations of CYP24A1, the Vitamin D 24-Hydroxylase Gene, Cause Long-standing Hypercalciuric Nephrolithiasis and Nephrocalcinosis

Hypercalciuria is the most common cause of kidney stone disease and genetic factors have an important role in nearly half of these cases. Recently loss-of-function mutations of CYP24A1, the gene encoding vitamin D 24-hydroxylase, were identified in idiopathic infantile hypercalcemia. We describe the clinical and molecular basis of severe long-standing kidney stone disease in adults caused by CYP24A1 mutations. Three subjects from 2 Israeli families with nephrolithiasis and nephrocalcinosis were clinically characterized. Genomic DNA was isolated from peripheral blood and sequencing of CYP24A1 was performed. All subjects presented with severe kidney stone disease, the cause of which was not discovered for decades despite extensive evaluation. They all had hypercalciuria, nephrocalcinosis and intermittent hypercalcemia, and chronic kidney insufficiency developed in the oldest subject. All patients had a typical pattern of test results, including normal-high serum calcium, low parathyroid hormone levels, high vitamin D 25-(OH)D3 and 1,25-(OH)2D3, and low 24,25-(OH)2D3. Overall 3 CYP24A1 loss-of-function mutations were identified, including a homozygous deletion (delE143) in consanguinous family 1, and compound heterozygous mutations L409S and the novel W268-stop in family 2. Loss-of-function mutations of CYP24A1 gene, encoding for 1,25-dihydroxyvitamin D3 24-hydroxylase, cause severe hypercalciuric nephrolithiasis and nephrocalcinosis. The mutations may present in adults and may lead to chronic renal insufficiency. Our results support a recessive mode of inheritance. CYP24A1 mutations should be considered in the differential diagnosis of hypercalciuric nephrolithiasis, especially as many adults are now prescribed supplemental oral vitamin D.

Milk–alkali syndrome sine alkalosis; an elusive cause of intermittent hypercalcemia

Milk–alkali syndrome sine alkalosis; an elusive cause of intermittent hypercalcemia

Hypercalcemia, Hypercalciuria, and Elevated Calcitriol Concentrations with Autosomal Dominant Transmission Due toCYP24A1Mutations: Effects of Ketoconazole Therapy

Mutations of the CYP24A1 gene, which encodes the 1,25-dihydroxyvitamin D-24-hydroxylase cytochrome P450, Cyp24A1, are predicted to result in elevated 1,25-dihydroxyvitamin D concentrations, hypercalcemia, hypercalciuria, nephrolithiasis, and bone disease. Treatment of hypercalcemia associated with CYP24A1 gene mutations has not been described. The genetic basis of a syndrome in a 44-yr-old Caucasian male characterized by intermittent hypercalcemia, hypercalciuria, elevated serum 1,25-dihydroxyvitamin D, undetectable serum 24,25-dihydroxyvitamin D, metabolically active nephrolithiasis, and reduced bone mineral density of the lumbar spine was examined. Sequencing of the CYP24A1 gene and biochemical and genetic analysis of seven family members in three generations was carried out. Because of hypercalcemia, hypercalciuria, and metabolically active nephrolithiasis, the patient was treated with a cytochrome 3A inhibitor, ketoconazole, 200 mg orally every 8 h, for 2 months. The sequence of the CYP24A1 gene showed two canonical splice junction mutations in the proband. Analysis of family members showed a phenotype associated one or both mutations, suggesting autosomal dominant transmission with partial penetrance of the trait. After therapy with ketoconazole, statistically significant reductions in previously elevated urinary calcium into the normal range were noted. Previously elevated serum 1,25-dihydroxyvitamin D and calcium concentrations decreased, and previously decreased PTH concentrations increased into the normal range, but the differences were not statistically significant. In a syndrome characterized by intermittent hypercalcemia, hypercalciuria, elevated 1,25-dihydroxyvitamin D, undetectable 24,25-dihydroxyvitamin D concentrations, splice junction mutations of the CYP24A1 gene, and autosomal dominant transmission of the trait, treatment with ketoconazole is useful in reducing urinary calcium.

Arterial calcification in chronic kidney disease

Hyperphosphatemia is associated with soft-tissue calcification and bone disease. Nephrologists prescribe phosphate binders to decrease dietary phosphate absorption, reduce serum phosphorus concentrations, and minimize the risk for soft-tissue calcification and bone disease. Recent data suggest that the dose of calcium used as a phosphate binder may contribute to the risk for cardiovascular calcification. Chronic positive calcium balance from diet, dialysis, and calcium-based phosphate binders or intermittent hypercalcemia may favor precipitation of calcium and phosphate into tissues. Calcium suppresses parathyroid hormone (PTH) secretion and bone turnover, limiting the ability of bone to incorporate calcium and phosphorus. Sevelamer, a non-absorbed polymer, allows physicians to bind dietary phosphate and decrease serum phosphorus without unwanted absorption of metals or calcium or over-suppression of PTH. In a comparative trial, calcium-based phosphate binders were associated with progressive coronary artery and aortic calcification that was attenuated by sevelamer. The optimal phosphate binder is one that controls hyperphosphatemia prevents soft-tissue calcification and preserves bone health.

Recurrence of hyperparathyroidism; a long-term follow-up after surgery for primary hyperparathyroidism.

In general it is thought that recurrence of primary hyperparathyroidism is a rare event. To our knowledge, however, only one large patient series has been reported with a mean of more than 7 years of follow-up. The aim of the present study was to determine the long-term recurrence rate in 785 out of 886 patients operated on for primary hyperparathyroidism and followed-up for a mean of 10.03 years after surgery. Medical records were scrutinised. The patients who were still alive answered a questionnaire and had laboratory tests. Follow-up data concerning the state of health, medical treatment, other diagnoses, renal function, and serum calcium and creatinine levels were found in the medical records of 203 patients, and were registered at the start of investigation of 582 patients. Intact parathyroid hormone values were determined in 252 patients. Recurrence rate and 95% confidence interval (C.I.) were calculated. Recurrence rate of hyperparathyroidism with constant or intermittent hypercalcaemia (n=39) was 4.97% (95% C.I.=3.45-6.74%) during a mean of 10 years of follow-up. Nine out of 39 had elevated serum creatinine levels. Recurrence rate of hyperparathyroidism with normal serum creatinine levels, including patients with normocalcaemia, intermittent hypercalcaemia, and constant hypercalcaemia was estimated to be 7-8% during a mean of 10 years of follow-up. Recurrence rate was determined with reasonable precision in this large patient series, and recurrence of hyperparathyroidism cannot be considered to be extremely rare, but it may occur more than 20 years after treatment in both single and multiple gland disease.

Preoperative normal level of parathyroid hormone signifies an early and mild form of primary hyperparathyroidism.

Contemporary patients are often diagnosed with mild or intermittent hypercalcemia. In addition, most studies demonstrate patients with parathyroid (PTH) levels in the upper normal range. The aim of the present investigation was to define subgroups of patients with mild primary hyperparathyroidism (pHPT), which could be of importance in the decision for or against surgical treatment. Two-hundred and eleven patients, operated for pHPT were investigated with biochemical variables known to reflect PTH activity, renal function, and bone mineral content. The preoperative diagnosis of pHPT was based on the presence of hypercalcemia combined with an inappropriate serum concentration of PTH. The mean age of the patients was 64 +/- 14 years and the mean serum level of calcium was 2.78 +/- 0.19 mmol/L. One hundred and sixty-two patients (77%) had raised levels of calcium and PTH the day before surgery (overt pHPT), 25 patients (12%) had a normal level of calcium and a raised PTH level (normal calcium group), and 20 patients (9%) had a raised level of calcium and a normal level of PTH (normal PTH group). In four patients the level of calcium and PTH was normal. Between-group analysis demonstrated no major difference in symptom and signs of pHPT. Except for lower adenoma weight, patients in the normal calcium group did not essentially differ from the patients in the overt pHPT group. However, patients in the normal PTH group were a decade younger, and had better renal function, lower bone turnover, and a preserved bone density compared with patients in the overt pHPT group. In conclusion, the data from the present investigation show that pHPT patients with a preoperative normal PTH level have an early and mild form of the disease. Furthermore, the serum calcium concentration does not reflect disease severity in pHPT.

Normal preoperative levels of parathyroid hormone signify a mild form of primary hyperparathyroidism

Abstract Background Primary hyperparathyroidism (pHPT) is characterized by an inappropriate serum level of parathyroid hormone (PTH) in relation to the serum level of calcium. Nowadays, patients often are diagnosed with an overtly asymptomatic pHPT with mild or even intermittent hypercalcaemia. Indeed, health screening surveys have shown that a significant proportion of patients with pHPT is normocalcaemic. Most studies also demonstrate patients with PTH levels in the upper normal range. The aim of the present study was to define subgroups of patients with mild pHPT, which potentially could give valuable insights into the pathogenesis of the disease. Methods Two hundred and seven consecutive patients, 157 women and 50 men, operated for pHPT were investigated with biochemical variables known to reflect PTH activity and calcium metabolism, and bone mineral content. The preoperative diagnosis of pHPT was based on the presence of hypercalcaemia combined with an inappropriate serum concentration of PTH. Thus, no patient was persistently normocalcaemic. Mean(s.d.) age of the patients was 64(14) years and mean(s.d.) serum level of calcium was 2·78(0·19) mmol l−1. On the basis of serum levels of PTH and calcium the day before surgery, patients were divided into subgroups. Results One hundred and sixty-two patients (78 per cent) had raised levels of PTH and calcium the day before surgery (group 1), 25 patients (12 per cent) had a raised level of PTH and normal level of calcium (intermittent normocalcaemia) (group 2) and 20 patients (10 per cent) had a normal PTH level and raised calcium level (group 3). Between-group analyses demonstrated differences between groups in age, bone density, renal function and adenoma weight, and serum levels of alkaline phosphate, osteocalcin and urate. Except for lower adenoma weights, patients in group 2 did not essentially differ from those in group 1. However, patients in group 3 were younger, had better renal function, lower biochemical bone turnover and higher bone mineral content than patients in the other two groups. Conclusion These data support the existence of subgroups of mild pHPT. Patients with a serum level of PTH within the normal range were characterized by less biochemical derangement and better bone mineral content. This finding suggests that PTH rather than calcium reflects the severity of the disease.

Risk Factors for Postoperative Hypocalcemia After Surgery for Primary Hyperparathyroidism—Invited Critique

Hypothesis: A variety of clinical and biochemical variables may be associated with hypocalcemia after surgery for parathyroid adenoma. Design : A prospective study of patients who underwent surgery for solitary parathyroid adenoma. Setting: A university hospital department of surgery. Patients: Eighty-six consecutive patients who underwent surgery for solitary parathyroid adenoma. Intervention: Parathyroidectomy according to the principles of unilateral neck exploration. Main Outcome Measures: Clinical and biochemical risk factors for early (≤4 days after surgery) and late (1 year after surgery) postoperative symptomatic and biochemical hypocalcemia. Results: Twenty-two patients developed early symptomatic hypocalcemia. The difference in total serum calcium levels between patients, with and without early symptomatic hypocalcemia, was evident on the third and fourth postoperative days. Serum level of osteocalcin greater than 6.0 μg/L, bilateral neck exploration, and history of cardiovascular disease were risk factors for symptomatic hypocalcemia (odds ratios [95% confidence intervals]: 4.4 [1.4-14.1], 3.8 [1.3-11.6], and 0.1 [0.02-0.60], respectively). Patients with up to 1 risk factor had a possibility of only 7% to develop early symptomatic hypocalcemia. One year after surgery, 16 patients had low levels of total serum calcium (late biochemical hypocalcemia) and were asymptomatic. Preoperative intermittent hypercalcemia was associated with an increased risk for late biochemical hypocalcemia (odds ratio, 3.9; 95% confidence interval, 1.0-16.3). Conclusions: Clinical and biochemical risk factors for early and late postoperative hypocalcemia in patients who underwent surgery for solitary parathyroid adenoma were found. A clinically useful prognostic index for early symptomatic hypocalcemia was constructed using these risk factors.

Risk factors for postoperative hypocalcemia after surgery for primary hyperparathyroidism.

A variety of clinical and biochemical variables may be associated with hypocalcemia after surgery for parathyroid adenoma. A prospective study of patients who underwent surgery for solitary parathyroid adenoma. A university hospital department of surgery. Eighty-six consecutive patients who underwent surgery for solitary parathyroid adenoma. Parathyroidectomy according to the principles of unilateral neck exploration. Clinical and biochemical risk factors for early (< or =4 days after surgery) and late (1 year after surgery) postoperative symptomatic and biochemical hypocalcemia. Twenty-two patients developed early symptomatic hypocalcemia. The difference in total serum calcium levels between patients, with and without early symptomatic hypocalcemia, was evident on the third and fourth postoperative days. Serum level of osteocalcin greater than 6.0 microg/L, bilateral neck exploration, and history of cardiovascular disease were risk factors for symptomatic hypocalcemia (odds ratios [95% confidence intervals]: 4.4 [1.4-14.1], 3.8 [1.3-11.6], and 0.1 [0.02-0.60], respectively). Patients with up to 1 risk factor had a possibility of only 7% to develop early symptomatic hypocalcemia. One year after surgery, 16 patients had low levels of total serum calcium (late biochemical hypocalcemia) and were asymptomatic. Preoperative intermittent hypercalcemia was associated with an increased risk for late biochemical hypocalcemia (odds ratio, 3.9; 95% confidence interval, 1.0-16.3). Clinical and biochemical risk factors for early and late postoperative hypocalcemia in patients who underwent surgery for solitary parathyroid adenoma were found. A clinically useful prognostic index for early symptomatic hypocalcemia was constructed using these risk factors.

Hypercalcemia in children: an overview.

Hypercalcemia occurs in children of all ages. A serum calcium level over 15 mg/dL can be life-threatening. The association between familial hypocalciuric hypercalcemia (FHH) and neonatal severe hyperparathyroidism (NHPT) has been discussed. FHH is characterized by a high serum calcium concentration, relatively low urine calcium excretion, and an inappropriately normal parathyroid hormone (PTH) concentration. On the other hand, NHPT is a rare disease characterized by markedly increased serum calcium (15 mg/dL) and PTH concentrations, and is fatal without parathyroidectomy early in life. Recently, a complementary DNA encoding an extracellular calcium-sensing receptor has been isolated. Furthermore, three mutations in the receptor gene in FHH and NHPT individuals have been described. Thus, heterozygotes and homozygotes of FHH may have an intermittent hypercalcemia and NHPT, respectively. Vitamin D-related hypercalcemia, and vitamin D intoxication and immobilization are also discussed.

Parathyroid Hormone Secretion and Serum Calcium Concentration - A Deterministic View of its Regulation

In seven normal men we investigated the basal secretion of PTH by blood sampling in 30 sec intervals for estimation of intact PTH and at 2-min intervals for measurement of ionized calcium. In 4 of these subjects we also investigated the PTH-secretion under conditions of intermittent hypercalcemia and hypocalcemia. Our measurements demonstrate the existence of three time scales in the secretion of PTH, viz. short-term pulses (faster than 2 min), an intermediate pattern of adjusting PTH levels to changed Ca2+ averages, and finally a long-term coupling between PTH and Ca2+ averages after 20 min. Ionized calcium controls the long-term regulation and intermediate adaptation mechanisms, but the short-term fluctuations seem to be due to spontaneous secretion.

Potential clinical use of the EDTA-infusion test.

The introduction of assays for the intact parathyrin (parathyroid hormone) has dramatically improved the diagnosis and follow-up of patients with primary hyperparathyroidism. However, in some patients with mild or intermittent hypercalcaemia, when plasma concentrations of intact parathyrin may be within the normal reference concentrations, the diagnosis of primary hyperparathyroidism may still be problematic. In these patients, the EDTA-infusion test is of potential value, as it also might be in patients with equivocal operative findings.

Normocalcemic hyperparathyroidism. Biochemical and symptom profiles before and after surgery.

Patients with normocalcemic hyperparathyroidism represent a diagnostic and therapeutic challenge. It is unclear to what extent these patients benefit from surgery in terms of correction of their serum chemistry abnormalities and their symptoms. We studied 142 patients: 23 with normocalcemic hyperparathyroidism (serum calcium levels below 2.62 mmol/L), 35 with intermittent hypercalcemia, and 84 with hypercalcemic hyperparathyroidism. Serum chemistry analyses and a standardized questionnaire of symptoms were completed before and after surgery. Overall, patients in the normocalcemic group reported a similar frequency of preoperative symptoms; had a similar reduction in postoperative symptoms; and had a similar normalization of serum calcium, parathormone, and phosphate levels as those in the two control groups. This study indicates that factors other than elevated serum calcium levels are in large part responsible for the symptoms of hyperparathyroidism and that these patients benefit from operation.