[Hematologic repercussions of disorders of thyroid secretion]

The effects on blood of abnormal thyroid hormone secretion were investigated in a prospective study involving 80 patients. Anaemia, when present, could usually be ascribed to association with another pathology. In non-anaemic patients an excess or a deficiency of thyroid hormones had opposite effects on erythrocytes. Leucocytes as a whole were not influenced by hypothyroidism, but untreated hyperthyroidism seemed to be responsible for a relative decrease in the number of neutrophils and a relative increase in the number of eosinophils and mononucleate cells. Platelet counts were unaffected by variations in thyroid hormone levels. Excluding the effects on blood of synthetic antithyroid drugs, the changes observed were generally reversible after correction of the abnormal hormone secretion.