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IntroductionNormocalcemic primary hyperparathyroidism (NHPT) is considered to be an early stage in the evolution of primary hyperparathyroidism (PHPT). To formulate a correct diagnosis, secondary hyperparathyroidism due to low calcium intake must be excluded. Whether dietary calcium intake might affect the clinical presentation of PHPT or NHPT has never been addressed consistently.ObjectiveTo describe patients with a diagnosis of NHPT or PHPT in relation to their calcium intake, through three standard validated questionnaires; to describe clinical, biochemical and radiological features of NHPT and PHPT patients compared to each other and to a control group.DesignCross-sectional study.SettingOutpatient, single academic medical center.Patients109 consecutive women recruited from February 2021 through April 2023. 54 patients with mild primary hyperparathyroidism (PHPT or NHPT) were age-matched with 55 unselected women undergoing bone density test screening due to recently diagnosed hormone-positive breast cancer. NHPT diagnosis was based on multiple determinations of both total and albumin-corrected serum calcium.InterventionsAdministration of all the following during routine endocrine consultation: a country-specific food-frequency questionnaire (LOC), the International Osteoporosis Foundation Calcium Calculator (IOF) and the National Osteoporosis Foundation calcium questionnaire (NOF).Main outcome measuresAny association between dietary calcium intake and clinical, radiological, or biochemical features.ResultsAll three questionnaires confirmed that NHPT patients had similar calcium intake as those with PHPT or controls. Biochemistries and bone turnover markers were similar between the two variants of hyperparathyroidism, except for serum calcium (sCa). NHPT patients had a significantly lower BMD and T-score at one-third distal radius compared to PHPT, while the prevalence of nephrolithiasis and clinical fractures were similar. Multivariate analysis investigating predictors of serum calcium showed that age, eGFR, calcium intake and 25(OH)D did not significantly affect serum calcium, while multivariate analysis investigating predictors of PTH (age, variant NHPT vs. PHPT, eGFR, calcium intake, 25(OH)D, cholecalciferol supplements) showed that calcium intake, variant and renal function, significantly influenced PTH levels.ConclusionsAll patients with primary hyperparathyroidism, particularly those with low dietary calcium intake, should be advised not to restrict dietary calcium to prevent further increase in PTH levels. Whether maintaining adequate calcium intake might positively impact bone density or biochemistries in patients refraining from surgery, should be addressed in longitudinal studies.

Introduction: Normocalcemic primary hyperparathyroidism is a variant of primary hyperparathyroidism with consistently normal albumin-adjusted or free-ionized calcium levels. It may be an early stage of classic primary hyperparathyroidism or could represent primary kidney or bone disorder characterized by permanent elevation of PTH level. Aim of the study: The study aims to compare the FGF-23 levels in patients with PHPT, NPHPT, and normal calcium and PTH levels. Methods: Our study included patients who were referred to the endocrinology clinic with a presumptive diagnosis of primary hyperparathyroidism, an isolated increased level of PTH, or reduced bone densitometry. For each patient, we performed blood analysis of FGF-23, calcium, phosphate, vitamin D [25(OH)D3], estimated glomerular filtration rate (eGFR), bone turnover markers, and urine analysis for calcium/creatinine ratio. Results: Our study included 105 patients. Thirty patients with hypercalcemic hyperparathyroidism (HPHPT group), thirty patients with elevated PTH and normal calcium levels (NPHPT group), and 45 patients with normal calcium and PTH levels in the control group. FGF 23 level was 59.5± 23 pg/ml in the NPHPT group, 77 ± 33 pg/ml in the HPHPT group, and 49.7 ± 21.7 pg/ml in the control group (p=0.012). The phosphate level was lowest in the HPHPT group: 2.9 ± 0.6 vs 3.5 ± 0.44 in the NPHPT and 3.8 ± 0.5 in the control groups (p=0.001). No differences were found in eGFR, 25(OH)D3, C-terminal telopeptide type I collagen (CTX) and procollagen type 1 N-terminal propeptide (P1NP) levels, and bone densitometry scores between the three study groups. Conclusion: Our findings suggest that NPHPT is an early stage of PHPT. Further studies are needed to determine the role of FGF-23 and its usefulness in NPHPT. [ABSTRACT FROM AUTHOR]

IntroductionNormocalcemic primary hyperparathyroidism is a variant of primary hyperparathyroidism with consistently normal albumin-adjusted or free-ionized calcium levels. It may be an early stage of classic primary hyperparathyroidism or could represent primary kidney or bone disorder characterized by permanent elevation of PTH level. Aim of the studyThe study aims to compare the FGF-23 levels in patients with PHPT, NPHPT, and normal calcium and PTH levels.MethodsOur study included patients who were referred to the endocrinology clinic with a presumptive diagnosis of primary hyperparathyroidism, an isolated increased level of PTH, or reduced bone densitometry. For each patient, we performed blood analysis of FGF-23, calcium, phosphate, vitamin D [25(OH)D3], estimated glomerular filtration rate (eGFR), bone turnover markers, and urine analysis for calcium/creatinine ratio.ResultsOur study included 105 patients. Thirty patients with hypercalcemic hyperparathyroidism (HPHPT group), thirty patients with elevated PTH and normal calcium levels (NPHPT group), and 45 patients with normal calcium and PTH levels in the control group. FGF 23 level was 59.5± 23 pg/ml in the NPHPT group, 77 ± 33 pg/ml in the HPHPT group, and 49.7 ± 21.7 pg/ml in the control group (p=0.012). The phosphate level was lowest in the HPHPT group: 2.9 ± 0.6 vs 3.5 ± 0.44 in the NPHPT and 3.8 ± 0.5 in the control groups (p=0.001). No differences were found in eGFR, 25(OH)D3, C-terminal telopeptide type I collagen (CTX) and procollagen type 1 N-terminal propeptide (P1NP) levels, and bone densitometry scores between the three study groups.ConclusionOur findings suggest that NPHPT is an early stage of PHPT. Further studies are needed to determine the role of FGF-23 and its usefulness in NPHPT.

Background: Raised parathormone (PTH) and normal calcium concentrations can be observed both in normocalcemic primary hyperparathyroidism (nPHPT) and in secondary hyperparathyroidism, e.g. due to vitamin D deficiency. We assessed the impact of season on the validity of diagnosis of nPHPT in terms of screening investigations to be performed in the primary care settings. Material and methods: On two occasions (March/April & September/October) we measured vitamin D (25OHD), PTH and total calcium in 125 healthy subjects, age range 6-50, not taking any vitamin D supplements. Results: In autumn there was an increase in 25OHD concentrations (from 18.1 ± 7.37ng/ml to 24.58 ± 7.72ng/ml, p<0.0001), a decline in PTH from 44.40 ± 17.76pg/ml to 36.63 ± 14.84pg/ml, p<0.001), without change in calcium levels. Only 45 subjects (36%) were vitamin D sufficient (25OHD>20/ml) in spring versus 83 (66.4%) in autumn, p<0.001. Elevated PTH concentrations were noted in 10 subjects in spring (8%) and in six subjects (4.8%) (p<0.05) in autumn. In spring, however, eight out of ten of these subjects (80%) had 25OHD<20 ng/ml, versus one in six (16.7%) in autumn (p<0.01). Normalization of PTH was observed in seven out ten subjects (70%), and all of them had 25-OHD<20 ng/ml in spring. Conclusions: In spring elevated PTH concentrations in the setting of normocalcemia are more likely to be caused by 25OHD deficiency rather by nPHPT. In contrast, in autumn, increased PTH concentrations are more likely to reflect nPHPT. We postulate that screening for nPHPT should be done in 25OHD replete subjects, i.e. in autumn rather than in spring. [ABSTRACT FROM AUTHOR]

BackgroundRaised parathormone (PTH) and normal calcium concentrations can be observed both in normocalcemic primary hyperparathyroidism (nPHPT) and in secondary hyperparathyroidism, e.g. due to vitamin D deficiency. We assessed the impact of season on the validity of diagnosis of nPHPT in terms of screening investigations to be performed in the primary care settings.Material and methodsOn two occasions (March/April & September/October) we measured vitamin D (25OHD), PTH and total calcium in 125 healthy subjects, age range 6-50, not taking any vitamin D supplements.ResultsIn autumn there was an increase in 25OHD concentrations (from 18.1 ± 7.37ng/ml to 24.58 ± 7.72ng/ml, p20/ml) in spring versus 83 (66.4%) in autumn, p