Skeletal effects of vitamin D deficiency among patients with primary hyperparathyroidism

Primary hyperparathyroidism

Primary hyperparathyroidism (PHPT), the most common cause of hypercalcemia, is most often identified in postmenopausal women with hypercalcemia and parathyroid hormone (PTH) levels that are either frankly elevated or inappropriately normal. The clinical presentation of PHPT includes three phenotypes: target organ involvement of the renal and skeletal systems; mild asymptomatic hypercalcemia; and more recently, high PTH levels in the context of persistently normal albumin-corrected and ionized serum calcium values. The factors that determine which of these three clinical presentations is more likely to predominate in a given country include the extent to which biochemical screening is employed, the prevalence of vitamin D deficiency, and whether a medical center or practitioner tends to routinely measure PTH levels in the evaluation of low bone density or frank osteoporosis. When biochemical screening is common, asymptomatic primary hyperparathyroidism is the most likely form of the disease. In countries where vitamin D deficiency is prevalent and biochemical screening is not a feature of the health care system, symptomatic disease with skeletal abnormalities is likely to predominate. Finally, when PTH levels are part of the evaluation for low bone mass, the normocalcemic variant is seen. Guidelines for surgical removal of hyperfunctioning parathyroid tissue apply to all three clinical forms of the disease. If guidelines for surgery are not met, parathyroidectomy can also be an appropriate option if there are no medical contraindications to surgery. In settings where either the serum calcium or bone mineral density is of concern, and surgery is not an option, pharmacological approaches are available and effective. Referencing in this article the most current published articles, we review the different presentations of PHPT, with particular emphasis on recent advances in our understanding of target organ involvement and management.

The impact of vitamin D deficiency on clinical, biochemical and metabolic parameters in primary hyperparathyroidism

BACKGROUND

It has been suggested that vitamin D deficiency is associated with worse clinical outcomes in primary hyperparathyroidism (PHPT). We aimed to evaluate the relationship between vitamin D deficiency and clinical, biochemical and metabolic parameters in PHPT patients.

METHODS

A total of 128 patients with biochemically confirmed PHPT were included. Patients were categorized as vitamin D deficient if 25-OH vitamin D was <50nmol/L, or normal if vitamin D was ≥50nmol/L. Biochemical parameters, bone mineral densitometry (BMD), and urinary tract and neck ultrasonography were assessed.

RESULTS

In the study group, 66 (51.6%) patients had vitamin D deficiency and 60 (48.4%) had normal vitamin D levels. Nephrolithiasis and osteoporosis were found in 26.6% and 30.5% of subjects, respectively. The prevalence of metabolic syndrome (MetS), obesity (BMI≥30kg/m²) and hypertension (HTN) were higher in the vitamin D deficient group when compared to the normal group (p=0.04, p=0.01 and p=0.03, respectively). There was no difference regarding the presence of nephrolithiasis and osteoporosis between the groups. The mean adenoma size was similar in both groups.

CONCLUSIONS

Vitamin D deficiency was not associated with osteoporosis, nephrolithiasis, adenoma size or biochemical parameters in PHPT. However, vitamin D deficiency may be a risk factor for developing HTN and MetS in PHPT.

Application of the Trabecular Bone Score in Clinical Practice

The trabecular bone score (TBS) was introduced as an indirect index of trabecular microarchitecture, complementary to bone mineral density (BMD), and is derived using the same dual energy X-ray absorptiometry images. Recently, it has been approved for clinical use in Korea. Therefore, we conducted a comprehensive review to optimize the use of TBS in clinical practice. The TBS is an independent predictor of osteoporotic fractures in postmenopausal women and men aged >50 years. The TBS is potentially useful in monitoring the skeletal effects of anabolic agents but not of antiresorptive agents. In postmenopausal women with type 2 diabetes mellitus, the TBS assesses osteoporotic fracture risk not captured by BMD. However, high body mass index and soft tissue thickness can cause underestimation of the TBS; however, this limitation has been improved in recent versions of the TBS software. However, a high precision error and low reproducibility limit the use of TBS. This review may provide information on the application of the TBS in clinical practice based on reliable evidence.

Low 25-Hydroxyvitamin D in Primary Hyperparathyroidism: Enhanced Conversion Into 1,25-Hydroxyvitamin D May Not Be "True" Deficiency

Vitamin D deficiency is reported in individuals with primary hyperparathyroidism (PHP). However, decreased 25OHD may be attributed to enhanced conversion into 1,25‐hydroxyvitamin D [1,25(OH)D]. To examine vitamin D metabolism in individuals with PHP, serum calcium, PTH, 25OHD, and 1,25(OH)D levels were determined in 210 adults: 102 with PHP, 40 with normal 25OHD, and 68 with vitamin D deficiency. Concentrations were redetermined in 37 individuals with PHP following vitamin D supplementation and 43 patients postsurgery. Comparisons were conducted by Student's t test and ANOVA. Correlations were assessed between PTH and 25OHD, 1,25(OH)D, and 1,25(OH)D/25OHD in individuals with PHP. Calcium, PTH, and 1,25(OH)D were higher (p < 0.001) in individuals with PHP (11.4 ± 0.4, 116 ± 21, 79 ± 6) than in individuals with normal 25OHD (9.6 ± 0.2, 49 ± 5, 57 ± 6) and vitamin D deficiency (9.3 ± 0.2, 62 ± 6, 32 ± 4). Compared with individuals with normal 25OHD (47 ± 5), 25OHD was lower (18 ± 3), but not different from subjects with vitamin D deficiency (15 ± 2). In individuals with PHP, vitamin D2 supplementation induced rises in 1,25(OH)D and calcium without lowering PTH, whereas postsurgery, calcium, PTH, 25OHD, and 1,25(OH)D normalized. Finally, in individuals with PHP, significant correlations (p < 0.01) were documented between PTH and calcium (r = 0.74), 25OHD (r = −0.43), 1,25(OH)D (r = 0.52), and 1,25(OH)D/25OHD (r = 0.46); and between 1,25(OH)D/25OHD and calcium (r = 0.47). Subnormal 25OHD in most individuals with PHP may be attributed to enhanced conversion to 1,25(OH)D—not “true” vitamin D deficiency—although in some patients, both PHP and vitamin D deficiency coexisted. Moreover, vitamin D supplementation exaggerated hypercalcemia in individuals with PHP. © 2020 The Author. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Associations between trabecular bone score and biochemistry in surgically vs conservatively treated outpatients with primary hyperparathyroidism: A retrospective cohort study

PURPOSE

Trabecular Bone Score (TBS) is a software-based method for indirect assessment of trabecular bone structure of the spine, based on analysis of pixels in dual energy x-ray absorptiometry (DXA) images. Few studies describe the use of TBS in patients with primary hyperparathyroidism (PHPT). This study aimed at further describing this relationship, investigating possible correlations between biochemistry, body mass index (BMI), fracture incidence and TBS.

METHODS

Cross-sectional study of 195 patients with verified PHPT, surgically (27) or conservatively (168) treated at the Department of Endocrinology, Aalborg University Hospital. TBS was acquired by reanalyzing DXA-images of the included subjects from the outpatient clinic. Biochemical variables were obtained from clinical routine blood samples taken in relation to the DXA-scans. History of fractures and medical history was obtained from radiology reports and medical charts.

RESULTS

Patients with active PHPT had a TBS-score signifying a partly degraded bone structure, whereas surgically treated patients had a normal bone structure as judged by TBS, though the difference in TBS-score was not statistically significant. Use of antiresorptive treatment was negatively associated with BMD but not TBS. No correlations between the biochemical variables and TBS were found. A negative correlation between TBS and BMI in patients with PHPT was present. Patients experiencing a fragility fracture had a significantly lowered TBS, BMD and T-Score.

CONCLUSION

Biochemistry does not seem to predict bone status in terms of TBS in patients with PHPT. TBS is negatively correlated to BMI, which is also seen in patients not suffering from PHPT. The lack of a predictive value for antiresorptive treatment for TBS may raise concern. TBS appears to have a predictive value when assessing risk of fracture in patients with PHPT.

MINI ABSTRACT

This cross-sectional study investigates possible correlations between biochemical variables, body mass index (BMI) and trabecular bone score (TBS) in 195 patients with primary hyperparathyroidism. It finds no correlation between biochemical variables and TBS, but finds a negative correlation between TBS and BMI and a clear association between fracture incidence and low TBS-score.

Primary Hyperparathyroidism

BACKGROUND

Primary hyperparathyroidism (PHPT), the most common cause of hypercalcemia, is most often identified in postmenopausal women. The clinical presentation of PHPT has evolved over the past 40 years to include three distinct clinical phenotypes, each of which has been studied in detail and has led to evolving concepts about target organ involvement, natural history, and management.

METHODS

In the present review, I provide an evidence-based summary of this disorder as it has been studied worldwide, citing key concepts and data that have helped to shape our concepts about this disease.

RESULTS

PHPT is now recognized to include three clinical phenotypes: overt target organ involvement, mild asymptomatic hypercalcemia, and high PTH levels with persistently normal albumin-corrected and ionized serum calcium values. The factors that determine which of these clinical presentations is more likely to predominate in a given country include the extent to which biochemical screening is used, vitamin D deficiency is present, and whether parathyroid hormone levels are routinely measured in the evaluation of low bone density or frank osteoporosis. Guidelines for parathyroidectomy apply to all three clinical forms of the disease. If surgical guidelines are not met, parathyroidectomy can also be an appropriate option if no medical contraindications are present. If either the serum calcium or bone mineral density is of concern and surgery is not an option, pharmacological approaches are available and effective.

CONCLUSIONS

Advances in our knowledge of PHPT have guided new concepts in diagnosis and management.

Primary hyperparathyroidism

Primary hyperparathyroidism (PHPT), the most common cause of hypercalcemia, is most often identified in postmenopausal women with hypercalcemia and parathyroid hormone (PTH) levels that are either frankly elevated or inappropriately normal. The clinical presentation of PHPT includes three phenotypes: target organ involvement of the renal and skeletal systems; mild asymptomatic hypercalcemia; and more recently, high PTH levels in the context of persistently normal albumin-corrected and ionized serum calcium values. The factors that determine which of these three clinical presentations is more likely to predominate in a given country include the extent to which biochemical screening is employed, the prevalence of vitamin D deficiency, and whether a medical center or practitioner tends to routinely measure PTH levels in the evaluation of low bone density or frank osteoporosis. When biochemical screening is common, asymptomatic primary hyperparathyroidism is the most likely form of the disease. In countries where vitamin D deficiency is prevalent and biochemical screening is not a feature of the health care system, symptomatic disease with skeletal abnormalities is likely to predominate. Finally, when PTH levels are part of the evaluation for low bone mass, the normocalcemic variant is seen. Guidelines for surgical removal of hyperfunctioning parathyroid tissue apply to all three clinical forms of the disease. If guidelines for surgery are not met, parathyroidectomy can also be an appropriate option if there are no medical contraindications to surgery. In settings where either the serum calcium or bone mineral density is of concern, and surgery is not an option, pharmacological approaches are available and effective. Referencing in this article the most current published articles, we review the different presentations of PHPT, with particular emphasis on recent advances in our understanding of target organ involvement and management.

Vitamin D and Trabecular Bone Score in a Group of Young Lebanese Adults

The relationship between vitamin D and trabecular bone score (TBS) in young adults remains unclear. The aim of this study was to explore the relationship between 25-hydroxyvitamin D [25(OH)D] serum levels and TBS in a healthy adult population. A total of 54 men and 61 women whose ages range from 18 to 35 participated in the present study. Participants with 25(OH)D insufficiency (between 21 and 29 ng/mL) were 55.7%, and those with 25(OH)D deficiency (≤20 ng/mL) were 11.4%. TBS positively correlated with 25(OH)D in men (r = 0.393; p <0.05) and women (r = 0.324; p < 0.05). In both genders, TBS was significantly higher in 25(OH)D-sufficient participants (≥30 ng/mL). The present study provides evidence that vitamin D positively affects bone health and suggests that maintaining adequate vitamin D status may be essential for optimal TBS values.

The impact of vitamin D status and parameters of calcium metabolism in patients with primary hyperparathyroidism

BACKGROUND

There is ample evidence associating vitamin D deficiency in primary hyperparathyroidism (PHP) patients with more severe disease manifestations and increased risk of postoperative hypocalcemia. Yet, there is limited data regarding the safety of vitamin D repletion in these patients.

AIM

To assess the safety of vitamin D repletion in PHP patients in a real-world setting.

DESIGN

We included patients with asymptomatic PHP and few symptomatic patients who declined surgery, followed in our clinic, and treated on a routine basis with 2000 IU/day of vitamin D3.

METHODS

Serum calcium (sCa), PTH, 25-hydroxyvitamin D, and 24 h urinary calcium (uCa) and creatinine collections were compared between the lowest and the highest vitamin D time points.

RESULTS

There were 40 patients of a mean age was 63 ± 10 years. 25(OH)D at lowest and highest vitamin D time points was 15.5 ± 6.2 ng/ml and 33.2 ± 8, respectively (P < 0.001). Serum calcium was not affected by the changes in vitamin D levels. In none of the patients did sCa exceed 11.5 mg/dL. uCa was 220 ± 110 mg/24 h at the lowest vitamin D time point and 260 ± 140 at the highest vitamin D time point (P = 0.14). uCa exceeded 400 mg/24 h in two vs. five patients (P = 0.23) at the lowest and highest vitamin D time points, respectively. PTH was not significantly different between the different vitamin D time points.

DISCUSSION/CONCLUSION

Vitamin D repletion in PHP seems safe. Considering the documented adverse influence of vitamin D deficiency in PHP, particularly on skeletal manifestations and on the postoperative course, vitamin D repletion is warranted.