Altered urinary beta 2-microglobulin excretion as an index of nephrotoxicity.

The experimental and clinical evidence indicate that beta 2-microglobulin (beta 2m) is actively reabsorbed from the glomerular filtrate by receptors on the brush border located in the proximal third of the proximal tubule. Increased beta 2m excretion in the absence of increased filtered load of beta 2m is indicative of nephrotoxicity. The data presented show that urine beta 2m increases and creatinine concentrations decrease within four hours of administration of diatrizoate megalumine (DMG). In 9 of the 20 patients, the urinary excretion of beta 2m (U beta 2m) increased to clearly abnormal values. In 12 of the 20 patients, the beta 2m excretion expressed as mg per g creatinine (Cr), increased from normal (less than 0.30) to an abnormal beta 2m excretion rate. The increased beta 2m excretion per g Cr occurring immediately after DMG administration lead us to conclude that this effect occurs when the nephrotoxic agent is present in the kidney. Based on these data we believe that the onset of abnormal urinary beta 2m excretion coincides with the presence of the causative agent. This criterion therefore, should prove to be useful in determining the time to conduct studies designed to search for the causative agent(s) in Balkan endemic nephropathy.

Vascular insufficiency in Okihiro's syndrome secondary to hypothenar hammer syndrome.

The presence of Okihiro's syndrome (congenital thenar hypoplasia and Duane's anomaly) in a patient became clinically significant when a hypothenar hammer syndrome developed. The ulnar artery occlusion resulted in a compromise of the hand's vascular supply because of a congenital hypoplastic radial artery. Resection of the thrombosed ulnar artery and insertion of an interposition vein graft restored circulation to the hand. Anatomic features in this case include a hypoplastic radial artery and double motor branch of the median nerve. Clinicians should consider Okihiro's syndrome in the differential diagnosis of thenar muscle atrophy since there are genetic, diagnostic, and clinical implications.

Renal artery stenosis with erythrocytosis after renal transplantation.

We present here results of studies on four patients (three men, one woman) who had had cadaver renal transplants and in whom renal artery stenosis and hypertension developed. Erythropoietin-dependent erythrocytosis developed in association with these changes in the three men. All patients had stable renal function and the hypertension was well controlled. Absolute erythrocytosis thought to be secondary to local renal hypoxia due to decreased renal blood flow developed in two of the men. Erythrocytosis developed in the other man but his RBC mass was at the upper limit of normal. In these patients, we suspect that the erythropoietin-dependent erythrocytosis is secondary to intrarenal hypoxia due to renal artery stenosis. Erythrocytosis or elevated erythropoietin levels failed to develop in the woman despite severe renal artery stenosis. Possible reasons for this discrepancy are discussed.