[Unexplained anaemia in men: be aware of hypogonadism].

Unexplained anaemia is not uncommon. We present two male patients suffering from longstanding mild anaemia, for which no cause could be found. We performed an extensive analysis, but there were no signs of malignant disease, chronic inflammation, renal failure, hypothyroidism, myelodysplastic syndrome, haemolysis or nutritional deficiencies. However, both patients had symptoms of hypogonadism, confirmed by biochemical testing. The 56-year-old man known with metabolic syndrome turned out to have secondary hypogonadism without a pituitary tumour and the 75-year-old man had primary hypogonadism. After exclusion of prostate carcinoma, testosterone substitution therapy was started in both patients, which improved their haematocrits and sexual and general well-being substantially. Testosterone exerts anabolic effects in multiple organ systems; in bone marrow it potentiates the stimulatory effect of erythropoietin on erythropoiesis. Primary hypogonadism frequently occurs in elderly patients, while secondary hypogonadism is frequently seen in middle-aged men with type 2 diabetes mellitus and obesity.