[Abnormal hemoglobins with high oxygen affinity in the differential diagnosis of polycythemia]

Retrospective Study of High Hemoglobin Levels in 56 Young Adults

Background

Erythrocytosis is a frequent request for consultation in the hematologic field. The diagnostic approach is well established in the general population but in a young adult, finding the etiology of erythrocytosis can be a real diagnostic challenge.

Methods

This is an observational retrospective unicentric study made at the Sherbrooke University Hospital Center, over a period of 20 years (1995 - 2015). Every patient aged between 16 and 35 years old with a significant elevation of hemoglobin or hematocrit was included (hemoglobin > 185 g/L and/or hematocrit > 0.52 in men; hemoglobin > 165 g/L and/or hematocrit > 0.48 in women).

Results

Totally, 426 patients met the inclusion criteria (over a total of 113,453 complete blood counts) but only 56 entered the study for investigations. The majority of patients were of male gender, 43% of the patients were obese, 59% were smokers and 38% used excess alcohol or recreational drugs. Twenty-five patients had the diagnosis of absolute erythrocytosis. Seven patients had the diagnosis of relative erythrocytosis and no cause could be identified in 24 patients. No primary erythrocytosis was found in this cohort. Among the 25 patients with secondary erythrocytosis, hypoxia was the most frequent etiology identified. Less than half of the patients in the cohort had long term follow-up. Search for JAK2 mutation and serum EPO dosage were performed in 17.9% and 23.2% of cases respectively. Seven patients were treated with aspirin and five patients had phlebotomies.

Conclusions

This retrospective study reveals an actual clinical management that is often discordant with the current recommendations and a frequent lack of follow-up after initial investigations. Harmonization of management of erythrocytosis appears to be highly desirable.

[Inherited primitive and secondary polycythemia]

Myeloproliferative disorders and secondary polycythemia cover most of the polycythemia cases encountered in daily practice. Inherited polycythemias are rare entities that have to be suspected when the classical causes of acquired polycythemia have been ruled out. Recent advances were made in the understanding of these pathologies, which are still little known to the physicians. This review reports the state of knowledge and proposes an algorithm to follow when confronted to a possible case of inherited polycythemia.

At high altitude in the Netherlands: secondary erythrocytosis due to HB-Malmö

We describe two patients, a father and a son, presenting with erythrocytosis. Evaluation showed no pulmonal or cardial disorders. Owing to an elevated erythropoietin level after phlebotomy, a physiological secondary polycythaemia was suspected. A haemoglobin electrophoresis showed that our patients have a haemoglobinopathy with high affinity for oxygen, called Hb-Malmö (exon 3: c.294 C>G p.His98Gln). Hb-Malmö is a congenital disorder located on a gene at chromosome 11, in the B-chain on codon 97, decoding the α-subunit and β-subunit of the haemoglobin. Through a mutation (CAC→CAG), histidine is replaced by glutamine. The mutation causes a disorder in the connection between the α1-subunit and β2-subunit of the haemoglobin structure. These connections are important sites for binding oxygen. Mutated haemoglobin has a preference for an oxygenated status, which implicates that there is an increased binding and decreased release of oxygen. To compensate, there will be an erythrocytosis to transport sufficient oxygen to the peripheral tissues.