Proximal renal tubular acidosis

Proximal renal tubular acidosis
Classification and external resources
OMIM 179830
DiseasesDB 11687
MedlinePlus 000497
MeSH D000141

Proximal renal tubular acidosis (pRTA) or Type 2 Renal tubular acidosis (RTA) is a type of RTA caused by a failure of the proximal tubular cells to reabsorb filtered bicarbonate from the urine, leading to urinary bicarbonate wasting and subsequent acidemia. The distal intercalated cells function normally, so the acidemia is less severe than dRTA and the urine can acidify to a pH of less than 5.3.[1] pRTA also has several causes, and may occasionally be present as a solitary defect, but is usually associated with a more generalised dysfunction of the proximal tubular cells called Fanconi syndrome where there is also phosphaturia, glycosuria, aminoaciduria, uricosuria and tubular proteinuria.

Patients with type 2 RTA are also typically hypokalemic due to a combination of secondary hyperaldosteronism, and potassium urinary losses - though serum potassium levels may be falsely elevated because of acidosis. Administration of bicarbonate prior to potassium supplementation might lead to worsened hypokalemia, as potassium shifts intracellularly with alkanization.

The principal feature of Fanconi syndrome is bone demineralization (osteomalacia or rickets) due to phosphate and vitamin D wasting.

Causes

Familial disorders

Acquired disorders

Treatment

Treatment consists of oral bicarbonate supplementation. However, this will increase urinary bicarbonate wasting and may well promote a bicarbonate diuresis. The amount of bicarbonate given may have to be very large to stay ahead of the urinary losses. Correction with oral bicarbonate may exacerbate urinary potassium losses and precipitate hypokalemia.[12] As with dRTA, reversal of the chronic acidosis should reverse bone demineralization.[13]

Thiazide diuretics can also be used as treatment by making use of contraction alkalosis caused by them.

See also

References

  1. ↑ Rodriguez Soriano J, Boichis H, Stark H, Edelmann CM (1967). "Proximal renal tubular acidosis. A defect in bicarbonate reabsorption with normal urinary acidification". Pediatr. Res. 1 (2): 81–98. PMID 6029811. doi:10.1203/00006450-196703000-00001.
  2. ↑ Gahl WA, Thoene JG, Schneider JA (2002). "Cystinosis". N. Engl. J. Med. 347 (2): 111–21. PMID 12110740. doi:10.1056/NEJMra020552.
  3. ↑ Golberg L, Holzel A, Komrower GM, Schwarz V (1956). "A clinical and biochemical study of galactosaemia; a possible explanation of the nature of the biochemical lesion". Arch. Dis. Child. 31 (158): 254–64. PMC 2011923 Freely accessible. PMID 13363463. doi:10.1136/adc.31.158.254.
  4. ↑ Matsuo N, Tsuchiya Y, Cho H, Nagai T, Tsuji A (1986). "Proximal renal tubular acidosis in a child with type 1 glycogen storage disease". Acta Paediatr Scand. 75 (2): 332–5. PMID 3457521. doi:10.1111/j.1651-2227.1986.tb10210.x.
  5. ↑ Morris RC (1968). "An experimental renal acidification defect in patients with hereditary fructose intolerance. I. Its resemblance to renal tubular acidosis". J. Clin. Invest. 47 (6): 1389–98. PMC 297294 Freely accessible. PMID 5653216. doi:10.1172/JCI105830.
  6. ↑ Hodgson SV, Heckmatt JZ, Hughes E, Crolla JA, Dubowitz V, Bobrow M (1986). "A balanced de novo X/autosome translocation in a girl with manifestations of Lowe syndrome". Am. J. Med. Genet. 23 (3): 837–47. PMID 3953680. doi:10.1002/ajmg.1320230311.
  7. ↑ Weibers, DO; Wilson, DM; McLeod, RA; Goldstein, NP (August 1979). "Renal stones in Wilson's disease". Am J Med. 67 (2): 249–54. PMID 463930. doi:10.1016/0002-9343(79)90399-1.
  8. ↑ Rochman, J; Lichtig, C; Osterweill, D; Tatarsky, I; Eidelman, S (October 1980). "Adult Fanconi's syndrome with renal tubular acidosis in association with renal amyloidosis: occurrence in a patient with chronic lymphocytic leukemia". Arch Intern Med. 140 (10): 1361–3. PMID 6775610. doi:10.1001/archinte.140.10.1361.
  9. ↑ Messiaen T, Deret S, Mougenot B, et al. (2000). "Adult Fanconi syndrome secondary to light chain gammopathy. Clinicopathologic heterogeneity and unusual features in 11 patients". Medicine (Baltimore). 79 (3): 135–54. PMID 10844934. doi:10.1097/00005792-200005000-00002.
  10. ↑ Riley AL, Ryan LM, Roth DA (1977). "Renal proximal tubular dysfunction and paroxysmal nocturnal hemoglobinuria". Am. J. Med. 62 (1): 125–9. PMID 13653. doi:10.1016/0002-9343(77)90357-6.
  11. ↑ Skinner R (2003). "Chronic ifosfamide nephrotoxicity in children". Med. Pediatr. Oncol. 41 (3): 190–7. PMID 12868118. doi:10.1002/mpo.10336.
  12. ↑ Rodríguez Soriano J (2002). "Renal tubular acidosis: the clinical entity". J. Am. Soc. Nephrol. 13 (8): 2160–70. PMID 12138150. doi:10.1097/01.ASN.0000023430.92674.E5.
  13. ↑ McSherry E (1981). "Renal tubular acidosis in childhood". Kidney Int. 20 (6): 799–809. PMID 7038264. doi:10.1038/ki.1981.213.
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