Endocrine Abstracts

Introduction: Vitamin D toxicity (VDT) is quite an uncommon condition which results from misperception between dosage regimens of vitamin D supplementation. VDT is diagnosed when Serum 25-hydroxyvitamin D levels are higher than 375 nmol/l (150 ng/ml). Vitamin D supplementation is easily accessible as over-counter medication and online. This report describes a patient who presented with severe hypercalcemia and acute kidney injury (AKI). Further assessment revealed that patient was taking mega dose of vitamin D over a period of at least 12 months.

Case Summary: A fit and healthy 71 years old male attended emergency department with symptoms of polyuria, polydipsia, constipation, lethargy, and weight loss. Initial Investigations revealed raised calcium (3.30 mmol/l), raised creatinine (465umol/l) and Urea (17.6 mmol/l) and low eGFR (10 ml/min/1.73m²). Work-up for the underlying causes of hypercalcemia showed: suppressed PTH (0.8pmol/l), negative myeloma screen and normal TSH (3.8mU/l). CT Thorax, Abdomen and Pelvis showed no evidence of malignancy. Further history revealed that he was taking 50,000 units/day of vitamin D (cholecalciferol) for more than 12 months. Vitamin D levels were checked, and it was more than 375nmol/l. He was treated with stopping vitamin D supplements, hydration, and steroids. Calcium levels dropped to 2.69 mmol/l although vitamin D level remains high at 375nmol/l. Patient was also started on calcitonin as his calcium levels kept fluctuating to higher levels.

Conclusions: Hypercalcemia due to VDT is uncommon but well recorded. Self-administration of vitamin D in uncontrolled and mega doses can result in Vitamin D Toxicity and related complications due to hypercalcemia. Looking for uncommon causes of hypercalcemia, in this case VDT, is advisable on top of taking good medication history for any complementary supplements. Increasing public awareness on the maximum daily requirement of vitamin D is highly recommended and is a good preventative practice.