The effect of growth hormone deficiency and of growth hormone substitution on blood volume and red cell parameters.

Abstract

Summary: Blood volume, plasma volume and red cell mass, red cell parameters, reticulocytes, serum iron, and total iron binding capacity were investigated. Fifty-nine growth-retarded children were studied: 27 children with idiopathic short stature (ISS) and 32 children with isolated growth hormone deficiency (GHD). Fifteen of the CHD patients were studied before treatment and again 3–6 months after onset of treatment with growth hormone, 3 GHD patients only before and 14 only during treatment. Blood volume, plasma volume, and red cell mass were significantly (P < 0.005) decreased by 15% in the untreated GHD patients and were normal in the children studied during treatment with growth hormone compared with the values in ISS patients. In the 15 GHD patients studied before and during treatment, blood volume, plasma volume, and red cell mass increased by 17% to normal values (P < 0.0005) on treatment with growth hormone. No significant differences were demonstrable between values related to actual body weight and to corrected weight for height. Hematocrit, mean corpuscular volume, and reticulocytes remained unchanged. Serum iron and total iron binding capacity were normal before treatment. Serum iron increased and total iron binding capacity decreased significantly during growth hormone substitution. In a pair of twins with Russell-Silver dwarfism and GHD, growth hormone increased blood volume, plasma volume, and red cell mass as in the other GHD patients. In another pair of twins with Russell-Silver dwarfism without GHD, growth the hormone was without effect on blood volume. Speculation: Our results of decreased blood volume and red cell mass in children with isolated GHD and the increase of blood volume and red cell mass during growth hormone treatment provide direct evidence that growth hormone is stimulating erythropoiesis. The less pronounced decrease of blood volume and red cell mass in our patients compared with the literature data obtained on panhypopituitary and hypophyseetomized subjects may indicate that growth hormone, thyroxin, and other hormones act synergistically on erythropoiesis. In children with panhypopituitarism or isolated GHD, blood volume, plasma volume, and red cell mass were found to be decreased by approximately 30% below normal (28, 30). Therefore, Shahidi and coworkers (30) recommended checking of blood volume in order to distinguish between dwarfism due to panhypopituitarism or GHD and idiopathic short stature. Their reports, however, include only one patient with isolved GUD (28), or do not differentiate between children with isolated GHD and panhypopituitarism (30). The effect of growth hormone on blood volume in isolated GHD has not yet been studied.