Introduction
Hypercalcaemia is commonly seen in hospitalised patients, with a common aetiology being primary hyperparathyroidism 1,2. It has been observed that many elderly patients admitted with an acute illness have transient hypercalcaemia. It is unclear whether this group of patients has mild underlying hyperparathyroidism.
Objective
To determine 1) the incidence of primary hyperparathyroidism in patients with transient hypercalcaemia 2) the contribution of calcium and vitamin D supplements in the development of transient hypercalcaemia
Methods
A retrospective analysis of laboratory data and medical records of patients with hypercalcaemia (defined as corrected serum Ca of >2.60) and normocalcaemia, was performed. Vitamin D levels, renal function, parathyroid hormone (PTH) and medications were also analysed.
Results
A total of 982 medical inpatients had their serum calcium checked between June-Dec 2013. A total of 104 (10.6%) patients (F 65/M 39, mean age 79 years) had transient hypercalcaemia, with normalisation of calcium during or after admission. A small proportion, N=25/104 (24%) had PTH checked; 10 of those 25 (40%) had elevated PTH and 15 (60%) had an inappropriately normal PTH. None had a suppressed PTH.
101 normocalcaemic patients (F 51/M 50, mean age 75 years) were also analysed as a control group. The proportion of patients with acute kidney injury (AKI) was similar in both groups (P = 0.382).
Calcium supplement intake was similar between the two groups (P=0.233), however there was a significantly higher rate of vitamin D use in the transient hypercalcaemic group (P=0.020). Interestingly, thiazide use was higher in the normocalcaemic group (P = 0.008).
Conclusion
Transient hypercalcaemia is common in hospitalised elderly patients. Hyperparathyroidism was the likely cause in all patients who had PTH measured. It was found that vitamin D supplementation appeared to be associated with transient hypercalcaemia, however calcium supplementation and AKI did not.