Blue Diaper Syndrome

Genetic disorder with defective transport for L-tryptophan resulting in blue urine.

Familial Hypercalcemia and Indicanuria; Drummond Syndrome; Familial Hypercalcemia with Nephrocalcinosis and Indicanuria; Tryptophan Malabsorption Syndrome.

Very rare with a frequency of 1:1117 consecutive patients studied for detection of inborn error of metabolism.

Either autosomal recessive or X-linked recessive inheritance.

Caused by a deficiency of a substrate-specific intestinal membrane transport system for L-tryptophan. The defect is located in the brush-border membrane of epithelial cells in the small intestine and kidney tubules, similar to Hartnup disease, cystinuria, iminoglycinuria, and lysine malabsorption syndrome.

Blue discoloration of the diapers starting in early infancy is secondary to bacterial degradation of tryptophan, producing indigo blue by enzymatic conversion of indolic compounds in the urine. Severe and prolonged hypercalcemia is frequent. Excess tryptophan is measured in the feces of the child, and increased tryptophan derivatives (indole acetic acid, indole lactic acid) found in the urine are of intestinal origin. These derivatives result from an increased concentration of tryptophan in the intestinal lumen. The plasma concentration of tryptophan is normal, but the increase following oral l-tryptophan intake is less than normal. Renal clearance of tryptophan is normal. In one report, the blue-greenish stool discoloration was attributed to a pigment derived from Pseudomonas aeruginosa.

Hypercalcemia and nephrocalcinosis are associated with failure to thrive, recurrent unexplained fever, infection, irritability, and constipation. Prognosis is unfavorable if complicated by nephrocalcinosis. Ocular abnormalities, such as microcornea, hypoplasia of the optic disc, and abnormal eye movements, have been described. The indoluria may look like the one in Hartnup syndrome, but a specific hyperaminoaciduria exists.

Evaluation of hydration, renal function, and hypercalcemia. Treatment of potentially associated infections. Rule out paralytic ileus.

A case of perioperative death has been reported after a mastoidectomy in an infant, but no data on the anesthetic technique used are available. Regional anesthesia can be performed. Because of a tendency toward dehydration, anesthetic drugs that may mask a low circulating volume and lead to vascular collapse should be avoided. Appropriate hydration and urinary output must be enforced. Paralytic ileus results in increased risk of regurgitation and aspiration during induction. Consequently, a rapid sequence induction is mandatory.

Avoid drugs with predominantly renal elimination (or consider reduced dose) in the presence of decreased kidney function.

Hartnup Disease: Autosomal recessive disorder caused by a defective transport of tryptophan and other neutral (i.e., monoamine-monocarboxylic) amino acids in the small intestine and kidneys. Patients may present with a pellagra-like skin condition, cerebellar ataxia, and gross aminoaciduria.

Diaminopentanuria: Increased renal clearance of cystine, lysine, arginine, and ornithine secondary to a dysfunction of the reabsorptive capacity of the renal tubules. In addition, defective intestinal absorption results in increased degradation of these amino acids by bacteria in the intestine.

Hyperprolinemia: Autosomal recessive inherited disorder with decreased renal tubular reabsorption of glycine and the imino acids proline and hydroxyproline. Patients with type II disease may be taking antiseizure medication, so epileptogenic drugs should be avoided.

Lysinuric Protein Intolerance: Autosomal recessive disease characterized by defective transport of the dibasic amino acids.

Purple Urine Bag Syndrome (PUBS Syndrome): Tryptophan (l-tryptophan) is a rarely used antidepressant drug. It decomposes in the gut to form indoxyl sulfate, which is absorbed and secreted in the urine (indican). Urinary organisms, such as Proteus and Klebsiella, have indoxyl sulfatase activity to metabolize indican to indigo, particularly in alkaline urine. In the other suggested pathway, once indoxyl sulfate comes in contact with air, it is oxidized to insoluble indigo, which causes the deep purple discoloration of the urine, the catheter, and the urine bag. Enteritis, pancreatic insufficiency, ileus, peritonitis (increased production), renal insufficiency (diminished excretion), bile acids, and steroidal conjugates also can cause a purple discoloration of the urine. Other reports suggest the color results from an interaction between indigo crystals in the urine and indirubin dissolved in the plastic bag for the urine. Most often, except for the scary color, this finding has no clinical relevance.