The spectrum of endemic renal tubular acidosis in the northeast of Thailand.
We have previously reported a high prevalence of endemic renal tubular acidosis (EnRTA) in the northeast of Thailand, and our subsequent studies provided evidence that K deficiency exists in the same region. Since tubulointerstitial damage is associated with K deficiency, we postulate that this might be implicated in the pathogenesis of EnRTA and, if so, that a spectrum of tubulointerstitial abnormalities can be anticipated. In this study we evaluated renal acidification ability in 4 patients and in 11 of their relatives. We used a 3-day acid load (NH4Cl 0.1 g/kg/day) followed by 20 mg oral furosemide and monitored the maximal renal concentrating ability using water deprivation and intranasal 1-deamino-D-arginine vasopressin. The results showed that the subjects could be divided into three groups; normal relatives of the patients, those with suspected renal tubular acidosis, and patients with overt EnRTA who had chronic metabolic acidosis and a low rate of excretion of NH4+. The rate of excretion of K was very low (20 +/- 4 mmol/day) in patients with EnRTA and in their relatives with suspected EnRTA. The transtubular K concentration gradient was also very low in their relatives, especially in patients with suspected EnRTA (2.8 +/- 0.2). With a 3-day NH4Cl load, the rate of excretion of NH4+ was very low in patients with EnRTA (32 +/- 9 mmol/day), and the relatives with suspected EnRTA also had a decreased capacity to excrete NH+4 (50 +/- 14 mmol/day). In contrast, the normal relatives excreted 92 +/- 12 mmol of NH+4/day. The patients with EnRTA could lower their urine pH to less than 5.5 after the acid loading (6.2 +/- 0.3). After furosemide (20 mg), the NH4+ excretion in the patients with EnRTA was lower than in the normal relatives. Moreover, the minimum urine pH in patients with EnRTA did not fall (6.1 +/- 0.2), but there was a fall to 4.8 +/- 0.1 in the patients with suspected EnRTA after furosemide treatment. In conclusion, there was a spectrum of tubulointerstitial abnormalities ranging from suspected to overt distal RTA in a geographic area known to have a high prevalence of K deficiency. K deficiency might be the important pathogenetic factor of EnRTA in the northeast of Thailand.
Vasuvattakul
S
S
Department of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand.
Nimmannit
S
S
Chaovakul
V
V
Susaengrat
W
W
Shayakul
C
C
Malasit
P
P
Halperin
M L
ML
Nilwarangkur
S
S
D000141:Acidosis, Renal Tubular / Q000097:blood / Q000453:epidemiology / Q000652:urine*; D000328:Adult; D000643:Ammonium Chloride / Q000008:administration & dosage / Q000494:pharmacology; D004232:Diuretics / Q000494:pharmacology; D019353:Endemic Diseases; D005260:Female; D005665:Furosemide / Q000494:pharmacology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007008:Hypokalemia / Q000652:urine; D007668:Kidney / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011191:Potassium Deficiency / Q000097:blood / Q000453:epidemiology / Q000652:urine; D000644:Quaternary Ammonium Compounds / Q000652:urine; D013785:Thailand / Q000453:epidemiology
D004232:Diuretics; D000644:Quaternary Ammonium Compounds; D000643:Ammonium Chloride; D005665:Furosemide