Endocrine Abstracts

Introduction: With increasing prevalence of hypogonadism, testosterone replacement therapy (TRT) remains the mainstay of treatment for male hypogonadism. Polycythaemia, the commonest reported side effect of TRT is often claimed to be less with transdermal preparations than intramuscular.

Case history: A 48 years gentleman, initially presented in primary care with reduced libido, erectile dysfunction(ED), low energy levels. Early morning testosterone levels (T-levels) were 10.9 nmol/l and 9.7 nmol/l (10.0-30.0 nmol/l) on two separate occasions for which he was started on transdermal TRT at 50mg/5g without any further evaluation to identify the etiology or free testosterone check or calculation. His pretreatment haemoglobin, haematocrit, thyroid, renal, lipid and bone profile, HbA1c, prostate specific antigen and liver function tests were normal but no gonadotrophins check. Within 8 weeks of TRT, his haemoglobin crept up from 167g/l to 194g/l (130-170g/l) and haematocrit from 0.50L/l to 0.58L/l (0.40-0.52L/l) when he was referred to secondary care. On review in secondary care his energy levels had improved but no improvement in libido and ED. Additionally he complained of facial flushing and generalized body itching worse after warm bath. His past medical history included well controlled primary hypothyroidism and hypertension. Examination showed extreme plethora, central obesity with BMI 39.6 kg/m2 and blood pressure of 150/80mmHg.

Investigations: Repeat blood tests confirmed polycythaemia, testosterone 6.7 nmol/l (10.0–30.0 nmol/l) and inappropriately normal follicle stimulating hormone 8.2U/l (1.3-19.3U/l), luteinizing hormone 3.7U/l (1.2-8.6U/l), normal prolactin and iron profile thus a likely diagnosis of functional hypogonadotropic hypogonadism secondary to obesity. Retrospective free testosterone calculation using formula of pretreatment T-levels revealed both normal free testosterone (0.391 nmol/l) and bioavailable (1.35 nmol/l) testosterone which indicates TRT wasn”t required in the first place.

Results and treatment: Given symptomatic polycythaemia, his TRT was immediately stopped and as per advice of haematology urgent venesection was done, prophylactic antiplatelet for 6-8 weeks and outpatient haematology follow up for secondary workup of polycythaemia which completely resolved after stopping TRT with haemoglobin of 175g/l and hematocrit 0.52L/l.

Conclusions and points for discussion: 1. Polycythaemia remains the commonest side effect of TRT even with transdermal preparations.2. In borderline or lower normal total testosterone or obesity, free testosterone should be checked using equilibrium dialysis or estimated using standard formula. 3. Once hypogonadism is confirmed, further workup to establish the cause should be considered specially gonadotrophins prior to TRT initiation. 4. Consideration of venesection and/or antiplatelet for 4-6 weeks to reduce vaso-occlusive events in severe symptomatic polycythaemia.