Endocrine Abstracts

Introduction: Granulomatous myositis (GM) is a very rare inflammatory condition and can cause PTH- independent hypercalcemia. The hypercalcaemia is due to the elevated levels of extrarenal 1,25 dihydroxy vitamin D produced by activated macrophages due to granulomatous inflammation. We present a case of very severe hypercalcemia due to GM.

Case presentation: An 82-year-old lady presented to the emergency department due to deterioration in renal function and 4 months history of lethargy, constipation, and reduced mobility. Initial investigations showed an adjusted serum calcium of 4.33 mmol/l, parathyroid (PTH) hormone of 1.5 nmol/l, vitamin D of 81 nmol/l and creatinine of 217 micromole/l. Intravenous fluid treatment followed by empirical Zoledronic acid normalised the calcium transiently and then rose back to 2.64 mmol/l. On further investigation, serum ACE was normal at 23 U/l (20-70) and serum 1,25 dihydroxy vitamin D was elevated at 189 pmol/l (20-120). PET CT showed intense uptake in the lower limb muscles and left biceps, and a targeted muscle biopsy confirmed Sarcoid-like granulomatous myositis. Serum creatine kinase was normal. This patient responded well clinically and biochemically to Prednisolone 30 mg daily. The calcium remains normal on a reducing dose of steroids, and she has returned to her previous level of independence.

Conclusion: The presence of very severe hypercalcemia and very low PTH in an elderly person usually suggests malignancy but was not the case here. The case is very unusual in that serum ACE level was normal unlike most other similar cases of isolated GM. It is also unusual to have a severe myositis with normal CK levels. We had a high degree of suspicion for other causes of PTH-independent hypercalcaemia, resulting in a PET scan request. We recommend considering PET scan in unexplained PTH independent hypercalcaemia, even with normal serum ACE level.