[50-year-old woman with elevated haemoglobin and iron deficiency]

Elevated haemoglobin and erythrocytosis are frequent causes for investigation.

A 50-year-old woman with elevated haemoglobin and erythrocytosis was referred to our hospital for investigation.

She had elevated serum erythropoietin and iron deficiency. Mutational status of the JAK2 gene was negative with respect to polycythemia vera, and no secondary reasons for polycythemia - including tumours - were revealed. A bone marrow biopsy and bone marrow smear showed a moderately increased number of lambda- positive monoclonal plasma cells, and small amounts of lambda light chains were detected in the urine. Serum electrophoreses showed no gammopathy. The reason for her elevated haemoglobin could be an erythropoietin-producing tumour or an idiopathic erythrocytosis based on a mutation in exon 12 of the JAK2 gene. Investigation of her plasma cells revealed a 10-fold increase in erythropoietin mRNA expression, indicating the reason for her elevated serum erythropoietin and haemoglobin values.