Seasonal hypercalcaemia; consider CYP24A1 mutation

Willows, Jamie; Sayer, John A.

doi:10.1093/qjmed/hcy265

Cited by 3 publications

(1 citation statement)

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“…Patients with increased calcium absorption should limit dietary calcium and vitamin D, avoid sun, and maintain hydration. Seasonal exacerbation of hypercalcemia has been described in patients with sarcoid and CYP24A1 variants . In patients with hypercalcemia related to solid tumors, bisphosphonates and/or denosumab were less effective if calcitriol was elevated .…”

Section: Observations and Discussionmentioning

confidence: 99%

Hypercalcemia

Walker

Shane

2022

JAMA

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ImportanceHypercalcemia affects approximately 1% of the worldwide population. Mild hypercalcemia, defined as total calcium of less than 12 mg/dL (&lt;3 mmol/L) or ionized calcium of 5.6 to 8.0 mg/dL (1.4-2 mmol/L), is usually asymptomatic but may be associated with constitutional symptoms such as fatigue and constipation in approximately 20% of people. Hypercalcemia that is severe, defined as total calcium of 14 mg/dL or greater (&gt;3.5 mmol/L) or ionized calcium of 10 mg/dL or greater (≥2.5 mmol/L) or that develops rapidly over days to weeks, can cause nausea, vomiting, dehydration, confusion, somnolence, and coma.ObservationsApproximately 90% of people with hypercalcemia have primary hyperparathyroidism (PHPT) or malignancy. Additional causes of hypercalcemia include granulomatous disease such as sarcoidosis, endocrinopathies such as thyroid disease, immobilization, genetic disorders, and medications such as thiazide diuretics and supplements such as calcium, vitamin D, or vitamin A. Hypercalcemia has been associated with sodium-glucose cotransporter 2 protein inhibitors, immune checkpoint inhibitors, denosumab discontinuation, SARS-CoV-2, ketogenic diets, and extreme exercise, but these account for less than 1% of causes. Serum intact parathyroid hormone (PTH), the most important initial test to evaluate hypercalcemia, distinguishes PTH-dependent from PTH-independent causes. In a patient with hypercalcemia, an elevated or normal PTH concentration is consistent with PHPT, while a suppressed PTH level (&lt;20 pg/mL depending on assay) indicates another cause. Mild hypercalcemia usually does not need acute intervention. If due to PHPT, parathyroidectomy may be considered depending on age, serum calcium level, and kidney or skeletal involvement. In patients older than 50 years with serum calcium levels less than 1 mg above the upper normal limit and no evidence of skeletal or kidney disease, observation may be appropriate. Initial therapy of symptomatic or severe hypercalcemia consists of hydration and intravenous bisphosphonates, such as zoledronic acid or pamidronate. In patients with kidney failure, denosumab and dialysis may be indicated. Glucocorticoids may be used as primary treatment when hypercalcemia is due to excessive intestinal calcium absorption (vitamin D intoxication, granulomatous disorders, some lymphomas). Treatment reduces serum calcium and improves symptoms, at least transiently. The underlying cause of hypercalcemia should be identified and treated. The prognosis for asymptomatic PHPT is excellent with either medical or surgical management. Hypercalcemia of malignancy is associated with poor survival.Conclusions and RelevanceMild hypercalcemia is typically asymptomatic, while severe hypercalcemia is associated with nausea, vomiting, dehydration, confusion, somnolence, and coma. Asymptomatic hypercalcemia due to primary hyperparathyroidism is managed with parathyroidectomy or observation with monitoring, while severe hypercalcemia is typically treated with hydration and intravenous bisphosphonates.

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Section: Observations and Discussionmentioning

confidence: 99%

Hypercalcemia

Walker

Shane

2022

JAMA

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Do the Heterozygous Carriers of a CYP24A1 Mutation Display a Different Biochemical Phenotype Than Wild Types?

Brancatella

Cappellani

Kaufmann

et al. 2020

The Journal of Clinical Endocrinology &Amp; Metabolism

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Context Human cytochrome P450 24 subfamily A member 1 (CYP24A1) loss-of-function mutations result in impaired activity of the 24-hydroxylase involved in vitamin D catabolism, thus inducing a vitamin D-dependent hypercalcemia. Homozygotes often present an overt clinical phenotype named Idiopathic Infantile hypercalcemia (IIH), whereas it is debated whether heterozygotes display an abnormal phenotype. Objectives To compare the clinical and biochemical features of heterozygous carriers of CYP24A1 variant and healthy wild-type controls, sharing the same genetic and environmental exposure. Methods A large family harboring the nonsense c.667A>T, p.Arg223* pathogenic variant in the CYP24A1 gene was evaluated. All subjects underwent clinical and biochemical evaluation and complete analysis of vitamin D metabolites using mass-spectroscopy including 1,24,25(OH)3D3. Subjects were divided according to their genotype in two groups: heterozygotes and wild-type for the CYP24A1 variant. Results The proband, a 40-year-old man, homozygous for p.Arg223* pathogenic variant, had a history of mild hypercalcemia with a seasonal trend, recurrent nephrolithiasis, and no episodes of acute hypercalcemia. He showed the highest serum levels of FGF23, the highest 25(OH)D3/24,25(OH)2D3 ratio and undetectable levels of 1,24,25(OH)3D3 which represent indicators of a loss-of function CYP24A1. Compared to the wild-types, heterozygotes had higher serum calcium and 25(OH)D3 concentrations (P=0.017 and P=0.025, respectively), without any difference in the other biochemical parameters and in the rate of nephrolithiasis. Conclusions Heterozygotes exhibit a biochemical phenotype different from that of wild-type subjects. In clinical practice, these individuals might require surveillance because of the potential risk of developing hypercalcemia and related clinical manifestations if exposed to triggering factors.

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