Endemic Primary Distal Renal Tubular Acidosis in Thailand

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The purpose of this project was to investigate possible causes of endemic renal distal tubular acidosis(EdRTA)in Northeastern part of Thailand. Two ways of trials were carried out, fieldwork and animal model experiments. Results obtained are as follows.1.Fieldwork : A research center has been settled at the Ubol District Hospital, Ubol Rajathanee, Ubol Prefecture, Thailand. EdRTA patients and healthy volunteers were selected for interview, clinical examinations and clinical biochemical analyses of blood and urine. Materials such as diet, soil, water and agricultural products were also sampled and brought to Japan for analysis of trace elements. Results are as follows.(1)Most patients were old aged females. They were small in height and light in body weight. Thus, BMI (body weight/hight^2)were low. Their urine gravity decreased.(2)Urinary beta2-microglobulin contents in EdRTA were significantly increased, and pH was high. Urinary creatinine concentrations decreased.(3)Urinary vanadium e … More xcretion was significantly increased in EdRTA.(4)Plasma Mg concentrations were high, and K was low in both sexes. Zn concentrations were high in male EdRTA, and Na was low in the female.2.Animal model with low Mg dietMg is an essential substrate especially for ATPases including Na, K-ATPase and H-ATPase, and low Mg sometimes is parallelled with low K. Usually Mg is reabsorbed in the thick ascending limb of Henle's loop(TAL). We, therefore, microdissected TAL and the collecting tubule(CT)from control and low K rat kidneys for Na, K-ATPase assay.(1)Na, K-ATPase activity in TAL from low Mg rats was significantly lowered.(2)The enzyme activity in CT was significantly increased. This finding is unexpected, since lowered Na, K-ATPase activity should initiate plasma K increase, resulting in dRTA theoretically. This discrepancy should be further investigated.3.Analysis of urinary proteins in hypo K rats.SD rats were treated with low K diet for 3 months, and their urinary proteins were electrophoresed. Total protein excretion was significantly increased. Electrophoretic patterns show increment of not only low molecular proteins but also high molecular proteins. This result is also slightly different from clinical data.In conclusion, these results clearly suggest that electrolytes and/or trace elements may play important roles in manifestation of EdRTA in Thailand. Less