Renal tubular acidsis (RTA) is a medical cnditin that invlves an accumulatin f acid in the bdy due ta failure f the kidneys tapprpriately acidify the urine. When bld is filtered by the kidney, the filtrate passes thrugh the tubules f the nephrn, allwing fr exchange f salts, acid equivalents, and ther slutes befre it drains intthe bladder as urine. The metablic acidsis that results frm RTA may be caused either by failure trecver sufficient (alkaline) bicarbnate ins frm the filtrate in the early prtin f the nephrn (prximal tubule) r by insufficient secretin f (acid) hydrgen ins intthe latter prtins f the nephrn (distal tubule). Althugh a metablic acidsis alsccurs in thse with renal insufficiency, the term RTA is reserved fr individuals with pr urinary acidificatin in therwise well-functining kidneys. Several different types f RTA exist, which all have different syndrmes and different causes.
Patients with prximal RTA may have high urinary calcium excretin; hwever, nephrcalcinsis and renal calculi are rare. This may be due tthe relatively nrmal rate f citrate excretin in these patients as cmpared with that f mst acidtic patients. Children with prximal RTA are likely thave grwth retardatin, rickets, stemalacia, and abnrmal vitamin D metablism. In adults, stepenia may develp but generally withut pseudfractures.
Autimmune disease. Classically Sjögren's syndrme, but it is alsassciated with systemic lupus erythematsus, rheumatid arthritis and even hypergammaglbulinemia. Hypkalaemia is ften severe in these cases. Hereditary causes include mutatins f Band 3 the baslateral bicarbnate transprter f the intercalated cell, which may transmit in an autsmal dminant fashin in western Eurpean cases, r in an autsmal recessive fashin in Suth East Asian cases. The Suth East Asian cases are assciated with mre severe hypkalemia. ther Hereditary causes include mutatins f subunits f the apical prtn pump vH+-ATPase, which transmit in an autsmal recessive fashin, and may be assciated with sensrineural deafness. Liver cirrhsis.
This is relatively straightfrward. It invlves crrectin f the acidemia with ral sdium bicarbnate r sdium citrate. This will crrect the acidemia and reverse bne demineralisatin. Hypkalemia and urinary stne frmatin and nephrcalcinsis can be treated with ptassium citrate tablets which nt nly replace ptassium but alsinhibit calcium excretin and thus dnt exacerbate stne disease as sdium bicarbnate r citrate may d.