- Nephrocalcinosis and renal stone disease
- Manifestations of acidosis with failure to thrive in children,
hypovolaemia, and tachypnea. - In contrary to distal RTA, the urine pH is variable. The morning
urine pH is less than 5.2. Infusion of NaHCO 3 to increase plasma
HCO 3 to normal will be followed by bicarbonaturia and increase in
urine pH (alkaline) in proximal RTA and not in distal RTA; since in
PRTA all HCO 3 above Tmax will be lost in urine.
Treatment:
A large amount of alkali is needed (3-10 mmol/kg/d). Potassium
supplement (KHCO 3 ) is needed because the correction of systemic
acidosis will lead to bicarbonaturia with more renal loss of potassium.
Abnormal Water Handling:
A. Nephrogenic diabetes Insipidus (NDI)
Normally, anti-diuretic hormone (ADH) will make the distal
nephron tubular basement membrane permeable to water with its
reabsorption from the tubular lumen. In NDI, the tubular basement
membrane is not responsive to ADH either due to defect in receptor site
for ADH or in the effector site; defect in adenylate cyclase enzyme with
reduced formation of cyclic AMP. Other mechanisms could be reduction
of the medullary hypertonicity as in chronic renal failure, prolonged low
protein intake and with the use of osmotic diuretics (mannitol).
Failure to respond to ADH will result in polyuria.