Hyponatremia in a patient with scleroderma renal crisis: a potential role of activated renin-angiotensin system

Hirotaka Fukasawa,Sayaka Ishigaki,Naoko Kinoshita,Ryuichi Furuya,Yoshihide Fujigaki,Shinsuke Isobe

doi:10.1186/1471-2369-13-47

Hirotaka Fukasawa, Sayaka Ishigaki + Show 4 more

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https://doi.org/10.1186/1471-2369-13-47

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BackgroundScleroderma renal crisis is an important complication of scleroderma (systemic sclerosis) that is associated with significant morbidity and mortality. On the other hand, hyponatremia has never been reported in patients with scleroderma renal crisis.Case presentationA 66-year-old man with scleroderma was admitted to our hospital for an evaluation of renal dysfunction and extreme hypertension. The laboratory evaluation revealed remarkably high plasma renin activity in association with microangiopathic hemolytic anemia, and the anti-RNA polymerase III antibody assessment was positive. The patient was diagnosed with scleroderma renal crisis and was started treatment with enalapril maleate, an angiotensin-converting enzyme inhibitor. During hospitalization, the patient developed symptomatic hyponatremia three times and each laboratory analysis revealed improperly high levels of antidiuretic hormone without signs of extracellular fluid volume depletion as well as remarkably high plasma renin activities and angiotensin levels. However, hyponatremia has not been demonstrated to occur as a result of combined therapy with candesartan cilexetil, an angiotensin II receptor blocker, and aliskiren fumarate, a direct renin inhibitor. The plasma renin activities and angiotensin levels were normalized and the renal function was maintained after treatment.ConclusionsTo our best knowledge, this is the first documented case of scleroderma renal crisis complicated with hyponatremia. This report also suggests that the activated renin-angiotensin system may play a role in the development of hyponatremia and that hyponatremia should be taken into consideration as a rare but possible complication associated with screloderma renal crisis.

Highlights

Scleroderma renal crisis is an important complication of scleroderma that is associated with significant morbidity and mortality
To our best knowledge, this is the first documented case of scleroderma renal crisis complicated with hyponatremia
This report suggests that the activated renin-angiotensin system may play a role in the development of hyponatremia and that hyponatremia should be taken into consideration as a rare but possible complication associated with screloderma renal crisis

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We report a rare case of SRC complicated with hyponatremia. To our best knowledge, this is the first case to be described in the literature. The effects of high levels of angiotensin II on the hypothalamic-neurohypophysial system are mediated via circumventricular organs (CVOs), such as the subfornical organ and the organum vasculosum of the lamina terminalis These organs anatomically lack the BBB, and as a result, angiotensins in the peripheral circulation are accessible to these sites [11]. Much higher ACE activities have been identified in CVOs compared to those in lungs [12] and Thunhorst et al [13] showed that the peripheral ACE blockade with anti-hypertensive doses could not inhibit the ACE activities in CVOs. it was possible that the remarkably high levels of angiotensin I reached in CVOs were locally converted into angiotensin II, that the converted (and likely high levels of ) angiotensin II stimulated ADH secretion, and that the first episode of hyponatremia developed on the 8th day of hospitalization.

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