High Calcitriol Levels Research Articles

Comprehension of Calcitriol Levels in Pregnant Women With Latent Tuberculosis and Immune Function in their Newborns.

Pregnant women with latent tuberculosis infection (LTBI) may develop active tuberculosis infection and could infect their neonates, which could impair the child's immune system due to infection-mediated immunological responses. In order to develop a preventative TB program in this study, we desired to understand the impact of calcitriol in LTBI pregnant women and immunological responses in neonates. In three hospitals in Medan, North Sumatra, we implemented a case-control design with 84 pregnant women in their third trimester and their newborns. We determined the levels of calcitriol, cathelicidin, and interferon gamma (IFN-γ) in women between December 2021 and July 2022. These measurements were then compared to the newborns' levels of calcitriol, cathelicidin, IFN-γ, and Toll-Like Receptor (TLR) 2. Analyses were performed using the Chi-squared and Fisher's tests, while Spearman correlations were employed to assess for correlations. 42 pregnant women with LTBI (interferon gamma release assay (IGRA) positive) and 42 pregnant women without LTBI (IGRA negative) participated in the study. The findings demonstrated that pregnant women with LTBI were at increased risk for calcitriol deficiency (Odds Ratio (OR) = 3.667, p = 0.006), which had an impact on the calcitriol levels of their unborn children (p = 0.038). TLR2 levels and calcitriol levels were substantially associated with LTBI pregnant women and their healthy neonates (p = 0.048; p = 0.005). Cathelicidin levels in the newborns of non-LTBI pregnant women were influenced by their higher calcitriol levels (p = 0.043). Pregnant women with LTBI had higher levels of cathelicidin and IFN-γ than those without it (p = 0.03; p = 0.001). Pregnant LTBI women's calcitriol levels had an impact on the calcitriol levels of their newborns. Mother's immunological responses and babies' calcitriol levels affected the levels of cathelicidin, IFN-γ, and TLR2 in newborns.

Analysis of Potential Vitamin D Molecule Biomarkers: Association of Calcitriol and Its Hydroxylation Efficiency Ratio with Cardiovascular Disease Risk in Rheumatoid Arthritis Patients.

Rheumatoid arthritis (RA) is a multifactorial autoimmune disease in which hypovitaminosis D by calcidiol quantification has been associated with disease severity. However, other vitamin D molecules could be implicated in RA pathophysiology and its comorbidities such as cardiovascular disease (CVD), which impacts the severity and mortality of RA patients. This study aimed to assess the relationship between calcidiol, calcitriol, its hydroxylation efficiency ratio, and the soluble vitamin D receptor (sVDR) and clinical and CVD risk variables to propose potential vitamin D molecule biomarkers for RA. A cross-sectional study of females was conducted on 154 RA patients and 201 healthy subjects (HS). Calcidiol, calcitriol, and the sVDR were measured in blood serum, and vitamin D hydroxylation efficiency was estimated using the calcitriol/calcidiol ratio score. CVD risk was calculated by the high-sensitivity C-reactive protein (hs-CRP) cutoff values. Disease activity was evaluated with the Disease Activity Score for 28 standard joints (DAS28-CRP). Results: The hydroxylation efficiency ratio and calcitriol serum levels were higher in RA patients with hypovitaminosis D (p < 0.001). Moreover, RA patients had a higher probability of a high hydroxylation efficiency ratio (OR = 2.02; p = 0.02), calcitriol serum levels (OR = 2.95; p < 0.001), and sVDR serum levels (OR = 5.57; p < 0.001) than HS. This same pattern was also observed in RA patients with high CVD risk using CRP serum levels; they showed a higher hydroxylation efficiency ratio (OR = 4.51; p = 0.04) and higher calcitriol levels (OR = 5.6; p < 0.01). Calcitriol correlates positively with the sVDR (r = 0.21, p = 0.03), CRP (r = 0.28, p < 0.001), and cardiometabolic indexes (p < 0.001) also showed discrimination capacity for CVD risk in RA patients with CRP ≥ 3 mg/L (AUC = 0.72, p < 0.01). In conclusion, hypovitaminosis D in RA patients was characterized by a pattern of a higher hydroxylation efficiency ratio and higher calcitriol and sVDR serum levels. Notably, higher calcitriol serum levels and a higher vitamin D hydroxylation efficiency ratio were associated with higher CVD risk in RA patients.

Low Expression of Calcitriol Level and Interleukin-10 and Hypoxia-inducible Factor-1 Alpha Expression on Placenta

BACKGROUND: Preeclampsia (PE) is the disease of theories and the second leading cause of maternal and perinatal morbidities and mortalities worldwide. These pathological disturbances will induce inflammation process, oxidative stress, and poor subsequent growth on the fetus including 32% of intrauterine growth restriction, 22% of prematurity, and 24% of neonatal sepsis and asphyxia. There are many theories about the mechanism of PE. In the molecularly level, it is suspected that the low level of calcitriol and interleukin (IL)-10 expressions and high expression of hypoxia- inducible factor (HIF)-1α are the risk factors of PE. AIM: The aim of this study was to prove the low calcitriol level, IL-10, and high expression of HIF-1α in the placenta as the risk factors of PE. METHODS: A nested case–control study was conducted at the Department of Obstetrics-Gynecology Sanglah and Wangaya Hospital Denpasar, Bali, from November 2020 to February 2021. RESULTS: A total of 64 samples of 20–40 weeks gestation age were selected by purposive consecutive sampling, divided into two groups consist of 32 PE as the cases and 32 non-PE as the controls. The material examination, 3 × 3 cm was isolated from the maternal placental surface, was performed at Laboratorium Biomedik Terpadu, Faculty of Medicine, Udayana University. We performed an ELISA technique to find out the calcitriol level; in the other hand, we used immunohistochemistry for detected expression of IL-10 and HIF-1-α. The results revealed the risk of PE in low placental calcitriol levels about 13.8 times higher than in high calcitriol levels (odds ratio [OR] = 13,801, 95% confidence interval [CI] = 4.048–47,050, p = 0.001. The risk of PE in low placental IL-10 expression about 6.6 times higher than in high IL-10 expression (OR = 6600; 95% CI = 2208–19,728; p = 0.001). The risk of PE in high placental HIF-1-α expression about 5.6 times higher than in low placental HIF-1-α expression (OR = 5.622; 95% CI = 1.922–16.450; p = 0.001). CONCLUSION: Low calcitriol level, low IL-10, and high HIF-1-α expression on the placenta were proved as significant risk factors for the development of PE.

Vitamin D Receptor (VDR) Genetic Variants: Relationship of FokI Genotypes with VDR Expression and Clinical Disease Activity in Systemic Lupus Erythematosus Patients.

Vitamin D (VD) deficiency is more frequent in systemic lupus erythematosus (SLE) patients than in control subjects (CS); genetic variants in the VD receptor (VDR) could contribute to the clinical disease activity. This study was aimed to determine the association of the VDR variants FokI (rs2228570), BsmI (rs1544410), ApaI (rs7975232), and TaqI (rs731236) with susceptibility to the disease, VD status, VDR mRNA expression, and clinical disease activity in SLE patients. A cross-sectional study was conducted in 194 SLE and 196 CS Mexican women. Immunoassays quantified serum calcidiol and calcitriol. Genotyping was performed by allelic discrimination assays and mRNA VDR expression by qPCR. The FokI variant was not in linkage disequilibrium with BsmI, ApaI, and TaqI&nbsp;VDR variants. SLE patient carriers of the TT FokI genotype showed higher clinical disease activity scores. Notably, the mRNA VDR expression was higher in SLE patients vs. CS, in active vs. inactive SLE patients, and in participants of both study groups with vitamin D deficiency, higher calcitriol levels, and TT FokI genotype carriers. In conclusion, the TT FokI VDR genotype was related to high VDR expression and clinical disease activity in systemic lupus erythematosus patients.

Association of High Calcitriol Serum Levels and Its Hydroxylation Efficiency Ratio with Disease Risk in SLE Patients with Vitamin D Deficiency.

Vitamin D (calcidiol) deficiency in systemic lupus erythematosus (SLE) is more frequent than in healthy subjects (HS); it is associated with clinical activity and damage in SLE. Although calcidiol is considered the best indicator of the vitamin D serum status, its deficiency could not reflect its hydroxylation efficiency ratio and calcitriol serum status. This study was aimed at assessing the association of calcidiol and calcitriol serum levels and its hydroxylation efficiency ratio with the risk to clinical and renal disease activities in SLE patients. A cross-sectional study was conducted in 308 SLE and HS women; calcidiol and calcitriol serum levels were evaluated by immunoassays. SLE patients showed lower calcidiol serum levels vs. HS (21.2 vs. 24.2 ng/mL; p < 0.001). Active SLE patients presented higher calcidiol/calcitriol ratio scores vs. inactive SLE patients (2.78 vs. 1.92 pg/ng; p = 0.02), and SLE patients with renal disease activity showed a pattern of calcidiol-deficient levels (19.5 vs. 25.3 ng/mL; p < 0.04) with higher calcitriol levels (47 pg/mL vs. 41.5 pg/mL; p = 0.02) and calcidiol/calcitriol ratio scores (2.13 vs. 1.54 pg/ng; p < 0.02) compared to SLE patients without renal disease activity. Calcidiol levels were negatively correlated with calcitriol levels (r = −0.26; p = 0.001) and urine proteins (mg/dL) (r = −0.39; p < 0.01). Regarding calcitriol levels, it was positively correlated with the blood lymphocyte count (r = 0.30; p < 0.001) and negatively correlated with the glomerular filtration rate (r = −0.28; p = 0.001). Moreover, the calcitriol/calcidiol ratio was positively correlated with urine proteins (r = 0.38; p < 0.01). The calcidiol deficiency (OR = 2.27; 95% CI = 1.15-4.49; p < 0.01), high calcitriol levels (T3rd, OR = 4.19, 95% CI = 2.23-7.90; p < 0.001), and a high calcitriol/calcidiol ratio score (T3rd, OR = 5.93, 95% CI: 3.08-11.5; p < 0.001) were associated with the risk for SLE. In conclusion, a pattern of calcidiol deficiency with high calcitriol serum levels and a high vitamin D hydroxylation efficiency ratio was associated with disease risk in SLE patients.

To Impact of Vit-D in Pulmonary Tuberculosis Patients Receiving DOTS

Introduction: Vitamin D, also known as calciferol, is a fat-soluble vitamin that helps regulate bone metabolism and calcium homeostasis in humans. Vitamin D from the skin and right is passed on by the liver to 25-hydroxyvitamin D (25 (OH) D, which is used to assess a patient's vitamin D status. The enzyme 25-hydroxyvitamin D-1hydroxylase converts 25 (OH) D into 1, 25-dihydroxy vitamin D (1,25 (OH) 2 D) in the kidneys. Vitamin D is essential for good health. Turning the immune system to the host (MTB). Cathelicidin, an anti-bacterial peptide that prevents mycobacterium from replicating macrophages, shown to be stimulated by vitamin D. In cases of tuberculosis, high levels of serum vitamin D and hypocalcaemia. Enhanced macrophages may be blamed for high calcitriol levels in granulomas. Low levels of vitamin D, on the other hand, linked and tuberculosis (PTB) in several studies conducted worldwide.&#x0D; Aim: Study of Vit-D In Pulmonary Tuberculosis Patients Receiving treatment.&#x0D; Materials and Methods: This study included 40 newly diagnosed PTB patients of both sex with the age group of 18-60. The patients were comprised before and after the DOTS therapy. Time period of this study were from September 2020 to Арril 2021 а nоn-rаndоmised соntrоlled trial.&#x0D; Results: The weight of patients before DOTS was decreased as compare to the weight after DOTS. The level of vitamin D significantly raised in newly diagnosed PTB patients while the vitamin D level was decreased after DOTS therapy.&#x0D; Conclusion: Decreased level of vit-D in the blood can be linked to an increased risk of tuberculosis. As a result, serum Vit-D levels in TB patients can be necessary to control, as Vit-D deficiency may develop without symptoms and intensify once TB therapy starts.

Systemic Jak1 activation causes extrarenal calcitriol production and skeletal alterations provoking stunted growth.

Mineral homeostasis is regulated by a complex network involving endocrine actions by calcitriol, parathyroid hormone (PTH), and FGF23 on several organs including kidney, intestine, and bone. Alterations of mineral homeostasis are found in chronic kidney disease and other systemic disorders. The interplay between the immune system and the skeletal system is not fully understood, but cytokines play a major role in modulating calcitriol production and function. One of the main cellular signaling pathways mediating cytokine function is the Janus kinase (JAK)--signal transducer and activator of transcription (STAT) pathway. Here, we used a mouse model (Jak1S645P+/- ) that resembles a constitutive activating mutation of the Jak1/Stat3 signaling pathway in humans, and shows altered mineral metabolism, with higher fibroblast growth factor 23 (FGF23) levels, lower PTH levels, and higher calcitriol levels. The higher calcitriol levels are probably due to extrarenal calcitriol production. Furthermore, systemic Jak1/Stat3 activation led to growth impairment and skeletal alterations. The growth plate in long bones showed decreased chondrocyte proliferation rates and reduced height of terminal chondrocytes. Furthermore, we demonstrate that Jak1 is also involved in bone remodeling early in life. Jak1S645P+/- animals have decreased bone and cortical volume, imbalanced bone remodeling, reduced MAP kinase signaling, and local inflammation. In conclusion, Jak1 plays a major role in bone health probably both, directly and systemically by regulating mineral homeostasis. Understanding the role of this signaling pathway will contribute to a better knowledge in bone growth and in mineral physiology, and to the development of selective Jak inhibitors as osteoprotective agents.

Systemic Jak1 activation provokes hepatic inflammation and imbalanced FGF23 production and cleavage.

Fibroblast growth factor 23 (FGF23) is a main regulator of mineral homeostasis. Low and high circulating FGF23 levels are associated with bone, renal, cardiovascular diseases, and increased mortality. Understanding the factors and signaling pathways affecting FGF23 levels is crucial for the management of these diseases and their complications. Here, we show that activation of the Jak1/Stat3 signaling pathway leads to inflammation in liver and to an increase in hepatic FGF23 synthesis, a key hormone in mineral metabolism. This increased synthesis leads to massive C-terminal FGF23 circulating levels, the inactive C-terminal fragment, and increased intact FGF23 levels, the active form, resulting in imbalanced production and cleavage. Liver inflammation does not lead to activation of the calcineurin-NFAT pathway, and no signs of systemic inflammation could be observed. Despite the increase of active intact FGF23, excessive C-terminal FGF23 levels block the phosphaturic activity of FGF23. Therefore, kidney function and renal αKlotho expression are normal and no activation of the MAPK pathway was detected. In addition, activation of the Jak1/Stat3 signaling pathway leads to high calcitriol levels and low parathyroid hormone production. Thus, JAK1 is a central regulator of mineral homeostasis. Moreover, this study also shows that in order to assess the impact of high FGF23 levels on disease and kidney function, the source and the balance in FGF23 production and cleavage are critical.

Jak1/Stat3 Activation Alters Phosphate Metabolism Independently of Sex and Extracellular Phosphate Levels

Introduction: Phosphate homeostasis is regulated by a complex network involving the parathyroid hormone (PTH), fibroblast growth factor 23 (FGF23), and calcitriol acting on several organs including the kidney, intestine, bone, and parathyroid gland. Previously, we showed that activation of the Janus kinase 1 (Jak1)-signal transducer and activator of transcription 3 (Stat3) signaling pathway leads to altered mineral metabolism with higher FGF23 levels, lower PTH, and higher calcitriol levels. Here, we investigated if there are sex differences in the role of Jak1/Stat3 signaling pathway on phosphate metabolism and if this pathway is sensitive to extracellular phosphate alterations. Methods: We used a mouse model (Jak1^S645P+/−) that resembles a constitutive activating mutation of the Jak1/Stat3 signaling pathway in humans and analyzed the impact of sex on mineral metabolism parameters. Furthermore, we challenged Jak1^S645P+/− male and female mice with a high (1.2% w/w) and low (0.1% w/w) phosphate diet and a diet with phosphate with organic origin with lower bioavailability. Results: Female mice, as male mice, showed higher intact FGF23 levels but no phosphaturia, and higher calcitriol and lower PTH levels in plasma. A phosphate challenge did not alter the effect of Jak1/Stat3 activation on phosphate metabolism for both genders. However, under a low phosphate diet or a diet with lower phosphate availability, the animals showed a tendency to develop hypophosphatemia. Moreover, male and female mice showed similar phosphate metabolism parameters. The only exception was higher PTH levels in male mice than those in females. Discussion/Conclusion: Sex and extracellular phosphate levels do not affect the impact of Jak1/Stat3 activation on phosphate metabolism.

Balancing Altered Calcium Metabolism with Bone Health in Sarcoidosis.

Abnormal calcium metabolism in sarcoidosis patients can lead to hypercalcemia, hypercalciuria, and kidney stones. Hypercalcemia in sarcoidosis is usually due to increased activity of 1α-hydroxylase in macrophages of pulmonary granulomata, resulting in low levels of 25-hydroxyvitamin D and high levels of calcitriol. Vitamin D supplementation may be dangerous for some sarcoidosis patients and is recommended only for those with decreased 25-hydroxyvitamin D and reduced or normal calcitriol level. Diagnosis, treatment of osteoporosis, and maintenance of bone health are complex issues for sarcoidosis patients. An approach to diagnosis and treatment of bone fragility is presented.

Mineral Homeostasis in Murine Fetuses Is Sensitive to Maternal Calcitriol but Not to Absence of Fetal Calcitriol.

Vitamin D receptor (VDR) null fetuses have normal serum minerals, parathyroid hormone (PTH), skeletal morphology, and mineralization but increased serum calcitriol, placental calcium transport, and placental expression of Pthrp, Trpv6, and (as reported in this study) Pdia3. We examined Cyp27b1 null fetal mice, which do not make calcitriol, to determine if loss of calcitriol has the same consequences as loss of VDR. Cyp27b1 null and wild-type (WT) females were mated to Cyp27b1+/- males, which generated Cyp27b1 null and Cyp27b1+/- fetuses from Cyp27b1 null mothers, and Cyp27b1+/- and WT fetuses from WT mothers. Cyp27b1 null fetuses had undetectable calcitriol but normal serum calcium and phosphorus, PTH, fibroblast growth factor 23 (FGF23), skeletal mineral content, tibial lengths and morphology, placental calcium transport, and expression of Trpv6 and Pthrp; conversely, placental Pdia3 was downregulated. However, although Cyp27b1+/- and null fetuses of Cyp27b1 null mothers were indistinguishable, they had higher serum and amniotic fluid calcium, lower amniotic fluid phosphorus, lower FGF23, and higher 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D than in WT and Cyp27b1+/- fetuses of WT mothers. In summary, loss of fetal calcitriol did not alter mineral or bone homeostasis, but Cyp27b1 null mothers altered mineral homeostasis in their fetuses independent of fetal genotype. Cyp27b1 null fetuses differ from Vdr null fetuses, possibly through high levels of calcitriol acting on Pdia3 in Vdr nulls to upregulate placental calcium transport and expression of Trpv6 and Pthrp. In conclusion, maternal calcitriol influences fetal mineral metabolism, whereas loss of fetal calcitriol does not. © 2018 American Society for Bone and Mineral Research.

Current concepts regarding calcium metabolism and bone health in sarcoidosis.

Vitamin D supplementation is widespread used in the general population. In sarcoidosis, up to 50% of patients, especially postmenopausal women and those taking corticosteroids, show evidence of increased bone fragility. The purpose of this review is to provide an evidence-based rationale on how to treat sarcoidosis patients with bone health issues. Evidence from observational studies show that decreased 25-hydroxy vitamin D is common in sarcoidosis. However, the great majority of sarcoidosis patents have normal or often elevated levels of 1,25-dihydroxy vitamin D (calcitriol), a marker associated with disease activity. High calcitriol levels may often be associated with hypercalcemia and hypercalcuria. The few interventional randomized controlled studies in the field, suggest that vitamin D supplementation may not be well tolerated because of hypercalcemia, moreover without substantial benefit on bone health and risk for fractures in these patients. Vitamin D supplementation may be withheld in sarcoidosis patients with bone fragility, unless calcitriol levels are below normal limits. A treating scheme is proposed.

FGF23 in kidney transplant: the strange case of Doctor Jekyll and Mister Hyde.

During the last decade, a new view into the molecular mechanisms of chronic kidney disease-mineral bone disorder (CKD-MBD) has been proposed, with fibroblast growth factor 23 (FGF23) as a novel player in the field. Enhanced serum FGF23 levels cause a reduction in serum phosphate, together with calcitriol suppression and consequent hyperparathyroidism (HPT). In contrast, reduced serum FGF23 levels are associated with hyperphosphatemia, higher calcitriol levels and parathyroid hormone (PTH) suppression. In addition, serum FGF23 levels are greatly increased and positively correlated with serum phosphate levels in CKD patients. In this population, high serum FGF23 concentration seems to predict the occurrence of refractory secondary HPT and to be associated with higher mortality risk in incident haemodialysis patients. In living-donor kidney transplant recipients, a faster normalization of FGF23 and phosphate levels with a lower prevalence of HPT, may be considered a major pathway to investigate.

Relationship of 1,25 dihydroxy Vitamin D Levels to Clinical Outcomes in Critically Ill Patients with Acute Kidney Injury.

Calcitriol [1,25(OH)2D] plays a central role in endocrine regulation of bone and mineral metabolism. Low 1,25(OH)2D levels in chronic kidney disease (CKD) are associated with increased cardiovascular morbidity and mortality. However, the role of 1,25(OH)2D in acute kidney injury (AKI) is unclear, with very limited data. This pilot study examined the relationship between 1,25(OH)2D levels in critically ill patients with AKI and clinical outcomes. Plasma 1,25(OH)2D, intact parathyroid hormone (iPTH), 25-OH Vitamin D (VitD), calcium and phosphorus were measured in 34 patients with AKI without pre-existing chronic kidney disease and 12 healthy controls. The mean 1,25(OH)2D levels were significantly lower in patients with AKI compared to controls, (42±5.6 pg/mL vs. 76.1±5.3 pg/mL, P <0.0001). The mortality in patients with AKI was 30%. 1,25(OH)2D levels were higher in non-survivors than survivors (62±41.4 pg/mL vs. 33.7±24.2 pg/mL respectively, P = 0.046) and serum phosphorus was also higher in non-survivors (6.2±2.1 mg/dL vs. 4.6±1.6 mg/dL, P = 0.019). However, on multivariate regression analysis, accounting for age and APACHE II score, higher levels of 1,25(OH)2D was not associated with mortality in critically ill patients with AKI. Mineral metabolism is dysregulated within days of acute renal injury in critically ill patients. On univariate analysis, high levels of calcitriol were associated with adverse clinical outcome in AKI. This association was not apparent after adjusting for age and APACHE II. Large controlled studies are needed to confirm these results, and determine if higher 1,25(OH)2D mediates worse outcomes in AKI.

Calcium Deficiency Reduces Circulating Levels of FGF23

Fibroblast growth factor (FGF) 23 inhibits calcitriol production, which could exacerbate calcium deficiency or hypocalcemia unless calcium itself modulates FGF23 in this setting. In Wistar rats with normal renal function fed a diet low in both calcium and vitamin D, the resulting hypocalcemia was associated with low FGF23 despite high parathyroid hormone (PTH) and high calcitriol levels. FGF23 correlated positively with calcium and negatively with PTH. Addition of high dietary phosphorus to this diet increased FGF23 except in rats with hypocalcemia despite high PTH levels. In parathyroidectomized rats, an increase in dietary calcium for 10 days increased serum calcium, with an associated increase in FGF23, decrease in calcitriol, and no change in phosphorus. Also in parathyroidectomized rats, FGF23 increased significantly 6 hours after administration of calcium gluconate. Taken together, these results suggest that hypocalcemia reduces the circulating concentrations of FGF23. This decrease in FGF23 could be a response to avoid a subsequent reduction in calcitriol, which could exacerbate hypocalcemia.

The Fibroblast Growth Factor 23: A New Player in the Field of Cardiovascular, Bone and Renal Disease

Recently, a new view into the molecular mechanisms of phosphate homeostasis and secondary hyperparathyroidism pathogenesis has been proposed, with Fibroblast Growth Factor 23 (FGF-23) as a novel player in the field. Enhanced serum FGF-23 levels cause a reduction in serum phosphate, together with calcitriol suppression and consequent hyperparathyroidism. In contrast, reduced serum FGF-23 levels are associated with hyperphosphatemia, higher calcitriol levels and parathyroid hormone (PTH) suppression. In addition, there are different FGF-23 actions that need investigation. In clinical practice, increased knowledge of mineral metabolism disorders alterations in chronic kidney disease (CKD) may be used to improve diagnostics and select future treatments. The discovery of FGF23 represents a novel factor in the pathogenesis of phosphate handling and secondary hyperparathyroidism in cardiovascular, bone and renal disease.

Evolution of Bone Disease at 2 Years After Transplantation: A Single-Center Study

Posttransplant bone disease is caused by renal osteodystrophy. We sought to examine bone mineral density (BMD) among 90 renal allograft recipients of mean age 42.7 ± 11.4 years to identify factors preventing bone loss at 2 years posttransplant. Subjects treated with cyclosporine or tacrolimus plus azathioprine/MMF and prednisone underwent BMD estimates of the lumbar spine (LS) and of the proximal femur using dual energy x-ray absorptiometry (DEXA) at 3 months and every 6 months for 2 years. We assayed markers of bone remodeling: intact parathyroid hormone (iPTH), calcitriol, osteocalcin, and carboxyterminal telopeptide of type I collagen on day 3, as well as month 1 and every 6 months after transplantation. At the initial measurement, we observed osteopenia (OSP) among 35% in the LS and 52% in the femur: there was osteoporosis in 8.3%. The prevalence of OSP increased during the first year, thereafter decreasing to the initial value, but the rate of osteoporosis did not change significantly (8.3% vs 6.0%). BMD and Z-score decreased during the first and increased in the second year; 27% of patients regained initial values and 38% higher ones. BMD gains in the LS and femur were observed among subjects with higher calcitriol levels during the first 6 months ( P < .01), higher osteocalcin ( P < .05), higher estimated glomerular filtration rate during 1–24 months and in the tacrolimus group. Improvement of LS BMD occurred in younger patients (38 vs 46 years; P < .027); BMD gain in the femur correlated with higher levels of iPTH from 1–12 months ( P < .01). The tacrolimus group showed higher Z-scores in the LS and femur at 24 months ( P < .05). Two years after transplantation >60% of recipients showed stabilization or gain in bone mass. A sufficient calcitriol level in the early transplant period, an adequate iPTH, good renal function, and tacrolimus therapy prevented BMD disease progression.

58-Year-Old Man With Fatigue and Flank Pain

58-Year-Old Man With Fatigue and Flank Pain

A Phase I trial of pulse calcitriol in patients with refractory malignancies

BACKGROUND Calcitriol is the principal biologically active metabolite of vitamin D. Calcitriol's activity against many neoplasms is well documented, but calcitriol's therapeutic application has been hampered by predictable hypercalcemia when it is given daily. Because laboratory data has suggested that intermittent exposure to high levels of calcitriol may be sufficient to produce antiproliferative effects, the authors developed a Phase I trial to determine the maximal tolerated dose, dose-limiting toxicity, and the pharmacokinetic profile of calcitriol given weekly by mouth. METHODS Patients with refractory malignancies were enrolled for 4 weeks of treatment followed by 4 weeks of observation. Reenrollment at a higher dose level was permitted for patients who had evidence of response or stable disease and no Grade 3 or greater toxicity. The starting dose was 0.06 μg/kg. RESULTS Fifteen patients received 20 cycles of therapy. Doses up to 2.8 μg/kg of calcitriol weekly produced no dose-limiting toxicity. While peak levels and the area under the serum concentration-time curve of calcitriol increased in a linear fashion at lower doses, saturable absorption was observed at doses above 0.48 μg/kg. Doses of 0.48 μg/kg and above produced mean peak calcitriol levels of 1625 pg/mL, approximately 25-fold greater than top normal levels and well within the therapeutic range suggested by in vitro experiments. Eight patients experienced self-limiting Grade 1 hypercalcemia. CONCLUSIONS Weekly dosing of oral calcitriol permitted substantial dose escalation with minimal toxicity. Peak serum calcitriol levels were in the predicted therapeutic range. A dose of 0.5 μg/kg was selected for evaluation in Phase II studies. Cancer 2001;91:2431–9. © 2001 American Cancer Society.

A Phase I trial of pulse calcitriol in patients with refractory malignancies

Calcitriol is the principal biologically active metabolite of vitamin D. Calcitriol's activity against many neoplasms is well documented, but calcitriol's therapeutic application has been hampered by predictable hypercalcemia when it is given daily. Because laboratory data has suggested that intermittent exposure to high levels of calcitriol may be sufficient to produce antiproliferative effects, the authors developed a Phase I trial to determine the maximal tolerated dose, dose-limiting toxicity, and the pharmacokinetic profile of calcitriol given weekly by mouth. Patients with refractory malignancies were enrolled for 4 weeks of treatment followed by 4 weeks of observation. Reenrollment at a higher dose level was permitted for patients who had evidence of response or stable disease and no Grade 3 or greater toxicity. The starting dose was 0.06 microg/kg. Fifteen patients received 20 cycles of therapy. Doses up to 2.8 microg/kg of calcitriol weekly produced no dose-limiting toxicity. While peak levels and the area under the serum concentration-time curve of calcitriol increased in a linear fashion at lower doses, saturable absorption was observed at doses above 0.48 microg/kg. Doses of 0.48 microg/kg and above produced mean peak calcitriol levels of 1625 pg/mL, approximately 25-fold greater than top normal levels and well within the therapeutic range suggested by in vitro experiments. Eight patients experienced self-limiting Grade 1 hypercalcemia. Weekly dosing of oral calcitriol permitted substantial dose escalation with minimal toxicity. Peak serum calcitriol levels were in the predicted therapeutic range. A dose of 0.5 microg/kg was selected for evaluation in Phase II studies.