Cystinuria

Rare. Disorder due to the renal reabsorption of dibasic amino acids (cystine, lysine, arginine, ornithine) inducing recurrent urinary lithiasis in childhood. These calculi consist of cystine which becomes insoluble when the urinary pH is < 7. Intestinal malabsorption of cystine is also present.


One distinguishes:

-         type 1: no absorption of cystine;

-         type 2: low absorption of cystine, the blood level of which does NOT increase after an oral load.

-         type 3: low absorption of cystine, the blood level of which does increase after an oral load


Autosomal recessive transmission of mutations in the SLC3A1 (chromosome 2) and SLC7A1 (chromosome 19) genes. Homozygous forms cause cystinuria with urinary symptoms. 


For heterozygous forms:

-         type 1: NO cystinuria

-         types 2 and 3: moderate cystinuria which becomes lithogenic in situations such as dehydration or acidification of the urine.


Other types: 
1.        type A, if the mutation is located on chromosome 2
2         type B if the mutation is located on chromosome 19 
3. type AB if the mutation is located on both chromosomes.


History: hematuria, anuria by urethral blockade with a calculus, attacks of renal colic, pyelonephritis, sometimes renal failure (acute or chronic). RX: multiple small echogenic lithiases .

Medical treatment: abundant drinks, alkalization the urine, salt-poor diet; if it fails, D-penicillamine (5-20 mg/kg/day) or alpha-mercaptopropionyl-glycine(10-30 mg/kg/j) that transform the cystine to cysteine which is more soluble. This treatment often poorly tolerated.

Surgical treatment: removal of the lithiasis (lithotripsy, uretero - or vesicotomy).


Anesthetic implications: 

check the renal function; frequent anesthesias for lithotripsy or other urological interventions; 

Side effects of medical treatment:

-        D-penicillamine: vomiting, diarrhea, stomatitis, interstitial lung disease, lupus, myasthenic syndrome, proteinuria, thrombocytopenia

-        alpha-mercaptopropionyl-glycine: proteinuria, thrombocytopenia, agranulocytosis.


Maintain high diuresis (moderate hypervolemia), including in the heterozygotes (siblings of an affected child).


References:

-         Buisson P, Haraux E, Hamzy M, Ricard J, Canarelli J-P, Boudaillez B, Braun K. 
Cystinurie chez l’enfant : à propos de 4 observations. 
Arch Pédiatr 2011 ; 18 : 553-7.


Updated: September 2019