Endocrine Abstracts

Case Summary: A 72 year-old man presented with a one month history of anorexia, weight loss, lethargy, constipation, increased thirst and generalised aches and pains. He had a background of hypertension, ischaemic heart disease, aortic stenosis, and a renal transplant 23 years ago with declining renal function. No significant abnormalities were noted on physical examination. Investigations confirmed hypercalcaemia, with serum calcium rising from 2.8–3.05 mmol/l. This was associated with a drop in parathyroid hormone (PTH) to 1pmol/l having been previously elevated at 15.7 pmol/l. He was on no medication that would interfere with calcium metabolism. The hypercalcaemia failed to respond to repeated intravenous bisphosphonate, steroids, and dietary calcium restriction. Abdominal ultrasound, skeletal survey, bone scan, serum/urine immunoelectrophoresis, serum angiotensin converting enzyme, and urine calcium/creatinine revealed no significant abnormalities. CT thorax/abdomen illustrated bilateral ground-glass opacification in keeping with pneumonitis but no other cause for hypercalcaemia. Bronchioalveolar aspirates disclosed positive immunofluorescence for PCP and he was commenced on co-trimoxazole. Serum calcium responded to treatment but over the next few weeks his renal function declined further requiring haemodialysis, and he subsequently died from septicaemia.

Discussion: This case illustrates a rare but important association of hypercalcaemia with an indolent presentation of PCP which has only rarely been reported previously. One report demonstrated that upto 20% of post-transplant patients with PCP infection may have hypercalcaemia, suggesting a more frequently occurring association than previously recognised. Hypercalcaemia following renal transplantation is often a consequence of persisting hyperparathyroidism and unregulated extra-renal production of 1,25-dihyroxyvitamin D in granulomatous conditions which may develop post-transplant. This latter mechanism is postulated to be responsible for hypercalcaemia occurring in PCP. Thus PCP should be considered in the differential diagnosis in cases of hypercalcaemia presenting with low PTH in the post-transplant cohort.

Declaration of interest: There is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.

Funding: No specific grant from any funding agency in the public, commercial or not-for-profit sector.