1 GeriPARTy Research Group, Jewish General Hospital, Montreal, Canada.
2 Department of Psychology, Concordia University, Montreal, Canada.
3 Department of Psychiatry, McGill University, 1033 Avenue des Pins, Montreal, H3A 1A1, Canada.
4 Centre for Clinical Epidemiology, Lady Davis Institute, Jewish General Hospital, Montreal, Quebec, Canada.
5 Division of Endocrinology and Metabolism, Jewish General Hospital, McGill University, Montreal, Quebec, Canada.
6 Douglas Mental Health University Institute, Montreal, Quebec, Canada.
7 National Institute for Health and Welfare, Helsinki, Finland.
8 Department of Psychiatry, Jewish General Hospital, Montreal, Canada.
9 Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, Canada.
10 Multiorgan Transplant Program, University Health Network and Divis

Background: Although lithium is considered the gold-standard treatment for bipolar disorder (BD), it is associated with a variety of major endocrine and metabolic side effects, including parathyroid hormone (PTH) dependent hypercalcemia. Aside from surgery and medication discontinuation, there are limited treatments for hypercalcemia. This paper will assess data from a randomized controlled trial (RCT).

Methods: This is a secondary analysis of an RCT that explored the effects of atorvastatin (n = 27) versus placebo (n = 33) on lithium-induced nephrogenic diabetes insipidus (NDI) in patients with BD and major depressive disorder (MDD) using lithium (n = 60), over a 12-week period. This secondary analysis will explore serum calcium levels and thyroid stimulating hormone (TSH) measured at baseline, week 4, and week 12.

Results: At 12-weeks follow-up while adjusting results for baseline, linear regression analyses found that corrected serum calcium levels were significantly lower in the treatment group (mean (M) = 2.30 mmol/L, standard deviation (SD) = 0.07) compared to the placebo group (M = 2.33 mmol/L, SD = 0.07) (ß = - 0.03 (95% C.I.; - 0.0662, - 0.0035), p = 0.03) for lithium users. There were no significant changes in TSH.

Conclusion: In lithium users with relatively normal calcium levels, receiving atorvastatin was associated with a decrease in serum calcium levels. Although exciting, this is a preliminary finding that needs further investigation with hypercalcemic patients. Future RCTs could examine whether atorvastatin can treat PTH dependent hypercalcemia due to lithium and other causes.