Unilateral renal ischemia causing the hyponatremic hypertensive syndrome in children—more common than we think?

Abstract

A case report in the journal Pediatric Nephrology describes a 15-month-old girl with the syndrome of hypertension and hyponatremia (HH syndrome) due to underlying unilateral renal artery stenosis. This syndrome is typically associated with hypokalemia and severe volume depletion and sometimes proteinuria, all of which, along with hypertension and hyponatremia, are usually corrected by resolution of the underlying renal ischemia. Gross and probably sudden activation of the renin-angiotensin system in response to renal ischemia is central to the pathophysiology although the cardiac atrial and B-type natriuretic peptides probably contribute also. Initial control of the severe hypertension may, in some cases, require careful volume repletion prior to introduction of blockade of the renin-angiotensin system in order to avoid first-dose hypotension, after which correction of the underlying renal ischemia is required. Whereas the syndrome has rarely been reported in children, it is possible that, as in adults, this reflects its lack of recognition by clinicians. The HH syndrome due to unilateral renal ischemia in children may be much more common than we think.

Hyponatremic hypertensive syndrome in pediatric patients: is it really so rare?

“…Laboratory findings in patients with HHS include hyponatremia, hypokalemia, hypochloremic alkalosis, and proteinuria, sometimes in the nephrotic range [2,8]. This was true in our patients as well.…”

“…This was true in our patients as well. Hypercalciuria and glycosuria have been less frequently reported [2,8]. All of our patients had marked hypercalciuria; none had glycosuria.…”

“…Data on the pediatric population are still sparse [5][6][7][8][9][10][11]. In an editorial commentary, Nicholls [2] suggested that HHS may be underdiagnosed in children and probably more common than previously thought. Our experience supports this assumption.…”

“…Activation of the reninangiotensin system (RAS) causes secondary hyperfiltration, pressure diuresis, and sodium loss from the contralateral, nonstenotic kidney. Renal handling of other solutes is also affected by this hyperfiltration state, as reflected by findings of hypokalemia, alkalosis, hypercalciuria, glycosuria, and proteinuria, sometimes within the nephrotic range [2,4,8,10]. Several authors reported reversible cortical hyperechogenicity of the nonstenotic kidney, probably a consequence of hyperfiltration and tubulointerstitial damage [10,14].…”

“…The combination of symptoms was first reported in 1950 by Hilden [1] in a series of five adult patients; the term HHS was introduced 15 years later by the Medical Research Council Blood Pressure Unit of Glasgow [1][2][3]. In 1999, Agarwal et al [4] studied a series of 32 adults with renovascular hypertension associated with HHS.…”