Endocrine Abstracts

Case history: A 53-year-old obsessive body builder, presented with severe constipation. He had used growth hormone, anabolic steroids and testosterone at variable doses for over 20 years. He had a protein intake of over 400 g/day over an extended period. He denied osmotic symptoms, joint or muscle pains, and excessive tiredness. Previously, he had benign prostatic hyperplasia and renal stone disease but was not on any prescription medication and took no over the counter ‘supplements’. He was a non-smoker and consumed no alcohol. There was no significant family history and his children were well.

Investigations: The following investigations were done at admission – i) corrected calcium – 3.66 (ref range), phosphate – 1.39 (0.80–1.50 mmol/l); ii) PTH – 2 (1.6–7.2 pmol/l); iii) urea 21.9 (ref range); iv) creatinine 319 (ref range) and eGFR 18; v) creatine kinase – 7,952 (ref range); vi) urine dipstick – protein 4+, glucose 4+, red cells 2+; vii) serum protein electrophoresis – normal pattern; viii) vitamin D – 46 (30 – 50 nmol/l), ix) vitamin A – 4.65 (1.10–2.60 μmol/l); x) CT of thorax, abdomen and pelvis – no abnormalities; xi) anti Jo-1, Ro-52+ve; xii) MRI of muscles – appearances suggestive of ‘inflammation’ and myositis with occasional calcification; xiii) normal thyroid function tests and a random glucose of 7.8 mmol/l; xiv) isotope renogram and GFR after rehydration – 68 ml/min; xv) muscle biopsy done – results awaited.

Results and treatment: A diagnosis of possible non-PTH mediated hypercalcaemia with acute kidney injury was diagnosed. He was rapidly rehydrated with normalization in serum calcium, his creatinine levelled to 180 μmol/l and creatine kinase to around 4,000 U/l. We believe the hypercalcaemia was caused by rhabdomyolysis induced by inflammatory myositis, excessive exercise (non-traumatic exertional rhabdomyolysis) and possible ingestion of myotoxins (hitherto unsubstantiated).

Conclusions and points for discussion: This subject presented with a possible rare cause for hypercalcaemia – rhabdomyolysis induced by a combination of factors in this obsessive body builder. Rhabdomyolysis produces hypercalcaemia by several mechanisms and is thought to be present in about 9% of these subjects. Points for discussion – i) the importance of isotope renography in subjects with high muscle mass and ‘impaired’ renal function; ii) why was PTH not completely suppressed despite significantly high serum calcium levels – is there coexistent primary hyperparathyroidism?; iii) could raised vitamin A levels play a role?