Mechanism of dilutional anemia in massive splenomegaly.

Twenty patients with anemia and massive splenomegaly were studied in order to elucidate the mechanism by which splenomegaly results in plasma volume expansion. In 18 patients, increased plasma volume accounted for most of the anemia. Fourteen patients had an exaggerated renin response to standing, mean 1967 +/- 613 (SE) ng angiotensin ll/100 ml plasma (p less than 0.05). The mean resting forearm blood flow was increased 3.47 +/- 0.32 (SE) ml/100 ml forearm tissue (p less than 0.001). The venous capacitance was normal, as contrasted to a marked decrease in venous capacitance in patients with anemia of comparable degree without splenomegaly. Cardiac indices were increased in 10 of 11 patients (range 4.1-8.1 liters/min/sq m). In nine of ten patients oxygen consumption was increased (range 147-231 ml/min/sq m). Splenectomy was performed on 14 patients. Splenic blood flow was elevated in four of four patients (range 750-2000 ml/min). Splenic A-V oxygen difference was exaggerated in seven of seven patients and in three of three patients splenic indocyanine-green dye dilution curve failed to show an early peak suggestive of A-V shunting in the spleen. Free portal pressure was elevated in 12 of 12 patients and decreased immediately after splenectomy. The intravascular albumin mass decreased in ten patients, was unchanged in three at 2-4 mo after splenectomy, and was accompanied by a rise in the plasma albumin concentration in nine. These data suggest that a flow-induced portal hypertension with expansion of the portal vascular space is an important early hemodynamic change. This finding, together with a decreased peripheral resistance, probably results in a decrease in effective intravascular volume, resulting in stimulation of the renin-angiotensin-aldosterone system and other renal hemodynamic changes necessary for salt and water retention. Splenectomy usually accomplishes a complete reversal of these abnormalities and correction of the anemia.

Radionuclide detection of a pheochromocytoma.

An area of increased radioactivity was visualized superior to the right kidney during the flow phase of a routine radionuclide renal angiography using 99mTc-Sn-DTPA. This same area failed to concentrate the radiopharmaceutical during delayed static images. This sequence suggested a highly vascular mass above the right kidney. The mass proved to be an adrenal pheochromocytoma as was suggested by the radionuclide study.