Fluctuating hypercalcaemia caused by cavitary Mycobacterium bovis pulmonary infection

Hypercalcaemia occurs in many granulomatous diseases. Among them, sarcoidosis and tuberculosis are the most common causes. Other causes include berylliosis, coccidioidomycosis, histoplasmosis, Crohn's disease, silicone-induced granulomas, cat-scratch disease, Wegener's granulomatosis and Pneumocystis carinii pneumonia. Hypercalcaemia in granulomatous disease occurs as a consequence of dysregulated production of 1,25-(OH)2 D3 (calcitriol) by activated macrophages in granulomas. Hypercalcaemia in patients with Mycobacterium tuberculosis infection has been reported in 0%-28% of cases. Uncultured bronchoalveolar lavage cells from patients with M. tuberculosis produce greater amounts of calcitriol compared with controls. Although Nayar et al described hypercalcaemia in a case of sepsis associated with intravesical Bacille Calmette Guerin therapy, there are no published reports describing hypercalcaemia in patients with pulmonary M. bovis infection. We describe a patient with M. bovis cavitary pulmonary infection with sustained hypercalcaemia that fluctuated and recurred repeatedly over the course of therapy, ultimately culminating in normalisation of serum calcium when therapy had led to cure. Treatment consisted of antituberculous therapy, oral corticosteroids and intravenous bisphosphonates with a favourable outcome.