1.
[Thiazide diuretics for hypertensive treatment induced severe hyponatremia with consciousness disturbance in two elderly cases].
Takeshita, M, Miyao, M, Mizuno, Y
Nihon Ronen Igakkai zasshi. Japanese journal of geriatrics. 2010;(3):257-61
Abstract
The salt intake of the Japanese is among the highest in the world, leading to a high prevalence of salt-sensitive hypertension. To prevent this, salt restriction, suppression of the rennin-angiotensin-aldosterone system, and natriuresis are important. Therefore, the use of a combination of an angiotensin II receptor blocker and thiazide diuretics is used for antihypertensive treatment. Some randomized controlled studies suggested that thiazide diuretics are useful not only to lower blood pressure, but also to prevent cardiovascular events and improve prognosis in the elderly, who are prone to being salt-sensitive. We encountered 2 elderly patients referred to our emergency room because of severe hyponatremia and consciousness disturbance, who had been treated with thiazide diuretics for 1 and 2 months, respectively. In both, hypernatriuria despite hyponatremia, slight dehydration, and refractory antidiuretic hormone (ADH) excess were observed, but activation of the rennin-angiotensin-aldosterone system was absent. Thyroid and adrenal functions were unremarkable. Theses phenomena have much in common with the condition called mineralcorticoid-responsive hyponatremia of the elderly (MRHE). Several weeks after discontinuation of diuretics, serum sodium values returned to normal levels, but transtubular potassium concentration gradient (TTKG) values were depleted despite slight hyperkalemia, and relative ADH excess was sustained, which suggested mineralocorticoid dysfunction and distal renal tubulointerstitial injury. Distal tubulointerstitial dysfunction is one of the most important causes of MRHE. On the basis of these 2 cases, we speculated whether distal tubulointerstitial injury may accelerate hyponatremia in the elderly. We need to check not only serum potassium, but also sodium levels, especially in elderly persons with suspected tubulointerstitial injury.
2.
An unusual patient with hypercalciuria, recurrent nephrolithiasis, hypomagnesemia and G227R mutation of Paracellin-1. An unusual patient with hypercalciuria and hypomagnesemia unresponsive to thiazide diuretics.
Kutluturk, F, Temel, B, Uslu, B, Aral, F, Azezli, A, Orhan, Y, Konrad, M, Ozbey, N
Hormone research. 2006;(4):175-81
Abstract
A 19-year-old female patient with hypercalciuria and recurrent nephrolithiasis/urinary tract infection unresponsive to thiazide type diuretics is presented. The patient first experienced nephrolithiasis at the age of 4 years. Afterwards, recurrent passages of stones and urinary tract infection occurred. On diagnostic evaluation at the age of 19 years, she also had hypocitraturia and hypomagnesemia. Her serum calcium concentrations were near the lower limit of normal (8.5-8.8 mg/dl; normal range: 8.5-10.5), her serum magnesium concentrations were 1.15-1.24 mg/dl (normal range: 1.4-2.5) and urinary calcium excretion was 900 mg/24 h. PTH concentrations were increased (110-156 pg/ml; normal range: 10-65). We tried to treat the patient with hydrochlorothiazide at a dose of 50 mg/day. During treatment with thiazide diuretics, PTH concentration remained high and the patient had recurrent urinary tract infections and passages of stones. Serum magnesium concentration did not normalize even under the parenteral magnesium infusion. Her mother had a history of nephrolithiasis 20 years ago. Severe hypomagnesemia in association with hypercalciuria/urinary stones is reported as a rare autosomal recessive disorder caused by impaired reabsorption of magnesium and calcium in the thick assending limp of Henle's loop. Recent studies showed that mutations in the CLDN16 gene encoding paracellin-1 cause the disorder. In exon 4, a homozygous nucleotide exchange (G679C) was identified for the patient. This results in a point mutation at position Glycine227, which is replaced by an Arginine residue (G227R). The mother was heterozygous for this mutation. G227 is located in the fourth transmembrane domain and is highly conserved in the claudin gene family. This case indicates the pathogenetic role of paracellin-1 mutation in familial hypomagnesemia with hypercalciuria and nephrocalcinosis and further underlines the risk of stone formation in heterozygous mutation carriers.