What are inherited tubular disorders in pediatrics?
Inherited tubular disorders are genetic diseases affecting specific segments of the renal tubules, leading to abnormal transport of electrolytes and solutes. Common pediatric examples include Fanconi syndrome, Bartter syndrome, Gitelman syndrome, and Liddle syndrome.
What is Fanconi syndrome in children?
Fanconi syndrome is a disorder of the proximal renal tubule causing impaired reabsorption of glucose, phosphate, bicarbonate, and amino acids. It leads to glycosuria, metabolic acidosis, hypophosphatemia, rickets, and growth failure in children.
What causes Fanconi syndrome in pediatrics?
Common causes include genetic diseases such as cystinosis, Wilson disease, hereditary fructose intolerance, tyrosinemia, and Lowe syndrome. Some drugs and toxins may also cause acquired Fanconi syndrome.
What is Bartter syndrome?
Bartter syndrome is a genetic disorder affecting the thick ascending limb of the loop of Henle. It causes salt wasting, hypokalemia, metabolic alkalosis, increased renin and aldosterone levels, and normal or low blood pressure.
What are the clinical features of Bartter syndrome in children?
Children with Bartter syndrome commonly present with polyuria, polydipsia, dehydration, failure to thrive, muscle weakness, hypokalemia, and metabolic alkalosis. Antenatal forms may present with polyhydramnios and prematurity.
What is Gitelman syndrome?
Gitelman syndrome is an autosomal recessive disorder caused by a defect in the sodium chloride cotransporter in the distal convoluted tubule. It leads to hypokalemia, metabolic alkalosis, hypomagnesemia, and low urinary calcium.
How is Gitelman syndrome different from Bartter syndrome?
Bartter syndrome affects the loop of Henle and causes hypercalciuria, whereas Gitelman syndrome affects the distal convoluted tubule and causes hypocalciuria with hypomagnesemia. Bartter usually presents earlier in childhood.
What is Liddle syndrome?
Liddle syndrome is a rare autosomal dominant disorder caused by overactivity of epithelial sodium channels in the collecting duct. It results in severe early-onset hypertension, hypokalemia, metabolic alkalosis, and suppressed renin and aldosterone.
What is the treatment for Liddle syndrome?
The treatment of choice is ENaC channel blockers such as amiloride or triamterene. Spironolactone is ineffective because aldosterone levels are already low.
How are inherited tubular disorders diagnosed in children?
Diagnosis involves clinical evaluation, serum electrolyte analysis, urine electrolyte studies, renal function tests, and genetic testing to identify the specific transporter defect.
