E72.01

Clinical Causes: Genetic mutations affecting the SLC3A1 or SLC7A9 genes, which code for amino acid transporters in the kidneys. Inheritance pattern typically follows an autosomal recessive manner, meaning an individual must inherit two copies of the mutated gene to develop the condition.

Key Symptoms: Recurring episodes of kidney stones, which may cause severe pain in the back or sides. Blood in the urine (hematuria) often visible or detected through testing. Frequent urinary tract infections. Pain or discomfort during urination. Nausea or vomiting associated with kidney stone passage. Occasional fever if infection develops due to urinary tract issues. Reduced urine output if stones cause obstruction.

Diagnosis Path: Diagnosis of cystinuria involves a combination of laboratory tests and clinical assessments. Urinalysis typically reveals high cystine levels, which can be confirmed through specialized tests such as cyanide-nitroprusside test strips. Blood tests may also be conducted to assess kidney function. Imaging studies like ultrasound, CT scans, or X-rays can detect kidney stones and assess their size and location. Genetic testing may further support diagnosis by identifying mutations in the responsible genes.

Treatment Protocols: Management of cystinuria focuses on preventing stone formation and facilitating the passage of existing stones. Approaches include: - Increasing fluid intake to dilute the urine and reduce cystine concentration. - Dietary modifications, such as reducing salt intake and limiting foods high in cysteine. - Use of medications like penicillamine, tiopronin, or captopril to bind cystine and make it more soluble. - Regular monitoring through urine tests and imaging examinations. - Procedures such as lithotripsy or surgical removal may be necessary for larger or obstructive stones. Early intervention and consistent management are key to reducing complications and preserving kidney function.