Vitamin D Toxicity Presenting as Altered Mental Status in Elderly Patients

Background and objective  Around 25-30% of elderly patients present to emergency departments (ED) with altered mental status (AMS), with hypercalcemia being one of the metabolic causes. Elderly patients, due to their multiple vulnerability factors and relative homeostenosis, are susceptible to alterations in mental state at even milder grades of hypercalcemia. There is a trend of overzealous prescription of higher doses of vitamin D in elderly patients for various ailments, which often exceeds the requirements of the patients. In this study, we aimed to establish vitamin D toxicity (VDT) as an underlying cause of AMS in elderly patients presenting to the hospital. Methods This was a descriptive case study conducted at a tertiary care university hospital in North India, from January 2015 to March 2020 for a total duration of five years. Elderly patients (aged ≥60 years) who were admitted with VDT as a cause for underlying hypercalcemia were included. The evaluation included patient history regarding the dosage of vitamin D received, route of administration, and biochemical parameters, such as serum calcium, intact parathyroid hormone (iPTH), 25-hydroxy vitamin D [25(OH)D], and albumin. All other potential causes for hypercalcemia and AMS were ruled out concurrently. Results A total of 19 patients were enrolled in the study, with a mean age of 72.3 years (range: 62-86 years). All patients had received injectable vitamin D formulation. The mean serum calcium among the patients was 12.52 ± 1.12 mg/dL (range: 11.2-15.7 mg/dL), whereas the mean 25(OH)D was 196.34 ± 70.44 ng/mL (range: 107-356 ng/mL). The mean cumulative vitamin D supplement intake was 2.594 ± 0.841 million IU (range: 1.2 million-4.2 million IU). While six patients had mild hypercalcemia, 12 had moderate, and one person had severe hypercalcemia, with altered sensorium (85%) being the most common complaint for presenting to ED, followed by generalized weakness (15%). Conclusion VDT can manifest with AMS as an initial presenting complaint. The geriatric population, due to various underlying vulnerability factors, is more susceptible than their younger counterparts. We strongly recommend that in elderly patients, higher doses of vitamin D should be prescribed only after checking their serum levels, and frequent monitoring of vitamin D should be performed.