Two women with spontaneous
hypokalemia (1 normotensive, 1 hypertensive in the absence of
renal artery stenosis), underwent unilateral
nephrectomy because of angiographic and/or split
renin-based suspicion of a reninoma. The normotensive patient clinically resembled
Bartter syndrome but had some elements suggestive of a
renin-secreting tumour, justifying surgical exploration and resection. The hypertensive patient presented clinically as a typical reninoma except for negative angiography. Surprisingly, the histology of the kidneys in both cases demonstrated juxtaglomerular
hyperplasia without evidence of reninoma. The postoperative follow-up (8 and 19 yrs, respectively) has shown in the normotensive patient a considerable improvement in the hyper-reninism and previously uncontrollable hypokalaemia and in the hypertensive patient a complete normalisation of BP,
renin and
electrolyte status. Although the histological condition of the contralateral kidneys remains unknown in both patients the preoperative lateralisation of hyper-reninism to one kidney, the postoperative complete relief of the hyper-reninism in the hypertensive patient after uninephrectomy and its decrease, exceeding that corresponding to the removal of one kidney in the normotensive patient, suggest that the juxtaglomerular
hyperplasia might have been unilateral or asymmetrical and that
nephrectomy may, unexpectedly, relieve the hyper-reninism caused by juxtaglomerular
hyperplasia. An increased unilateral susceptibility to trophic or
renin-releasing factors or an asymmetrical abnormality in the macula densa-initiated mechanism of juxtaglomerular
hyperplasia may be implicated in this disorder.