Endocrine Abstracts

A 60 years old male patient was referred due to persistent asymptomatic hypocalcaemia with an adjusted calcium ranging between 1.9 to 2.08 mmol/l. He has always had normal Kidney functions, Magnesium, Phosphate and Vitamin D and normal PTH (ranging between 2.6-3.2 pmol/l) when checked. To investigate the hypo-parathyroidism, Genetic testing was done and he was found to be heterozygous for a pathogenic CASR variant consistent with Autosomal dominant hypocalcaemia type 1 (ADH1). He was started on Vitamin D replacement (Calci D 1000 mg/1000 units once daily) and he was also investigated for the possible complications by having an Ultrasound (KUB) which didn’t show any stones. ADH1 is a rare form of hypo-parathyroidism due to activating variants of the calcium-sensing receptor gene (CASR) altering the set point for extracellular calcium, resulting in inadequate parathyroid hormone (PTH) secretion and inappropriate renal calcium excretion leading to hypocalcemia and hypercalciuria Despite our patient being asymptomatic, ADH1 is often associated with severe symptomatology at presentation with an increase in the risk of renal complications after initiation of conventional therapy. Conventional treatment consists of active vitamin D analogues and/or calcium supplements. Thiazides and a low sodium diet may be considered. Raising serum calcium may induce or exacerbate pre-existing hypercalciuria, increasing the risk for long-term renal complications, therefore, treatment aims to achieve serum calcium levels within or just below the lower normal reference range for calcium. Distinct from postsurgical hypoparathyroidism, ADH1 is often associated with more pronounced hypercalciuria, especially after the initiation of treatment. Assessment for complications includes nephrocalcinosis, nephrolithiasis, renal impairment. Regular 6 monthly follow-up includes monitoring adjusted calcium, magnesium, phosphate ,Vitamin D , 24-hours urinalysis of calcium and creatinine. Renal ultrasonography (RUS) or CT should be performed at the initial assessment. Serum calcium should be re-measured within days after adjustments in treatment.