Gelatinous transformation (GT) of the bone marrow is rare and associated with a variety of clinical diseases from malignancy to chronic infection in combination with malnutrition or wasting. A new clinical picture of GT has emerged with excessive physical activity in combination with a voluntary insufficient calorie intake in the young adult male. Overtraining syndrome and systemic inflammation may play a role in the pathogenesis of GT in these patients, but further studies on GT and the effect of training and overtraining on the bone marrow are needed.

A 32-year-old man was admitted to the hospital because of oedema and 8 kg of gained weight. The oedema decreased spontaneously over weeks and there was no evidence for a nephrotic syndrome; however, the blood tests revealed a moderate pancytopenia. The patient practiced excessive physical activity at work and in his spare time, and kept a very thorough training and weight diary. Owing to a high intake of energy and protein drinks he tried to optimise his physical performance and kept a normal body mass index at 23.7. A bone marrow biopsy showed gelatinous bone marrow transformation, normally seen in critically ill patients or those with severe malnutrition. In this case, the cause is presumed to be excessive physical activity/overtraining in combination with relatively insufficient nutrition.