CAKUT

Question 1

Nephronopthisis (NHNP)

Answer 1

Autosomal recessive genetic disorder
Genes encoding proteins involved in cilia function

Characterised by:

1. Reduced concentrating ability
   - bland sediment
   - polyuria & polydipsia, not responding to fluid restriction/vasopressin
   - sodium wasting (hypovolemia, hyponatremia)
2. Chronic tubulointerstitial nephritis
3. Early progression to ESRD (mean age 13yrs)
4. Normal sized kidneys, absence of haematuria & proteinuria, hypertension

Variants based on age of presentation
Infantile- onset 1yr: NHNP2 gene
Juvenile- onset 13yrs (most common): NHNP1 gene
Adolescent- onset 19yrs: NHNP3 gene

Other features

• Retinitis pigmentosa 20% patients (Senior-Loken syndrome)
• Poor growth (due to chronic dehydration & CKD)
• Anemia
• Metabolic acidosis
• Uremia (nausea, anorexia, weakness)
• Proteinuria is a late sign (2nd glomerulosclerosis)

Question 2

Medullary Cystic Kidney Disease (MCKD)

Answer 2

Autosomal dominant

• MCKD1 - MUC1 gene
• MCKD2 - UMOD gene

Tubuluointerstitial fibrosis, atrophy
Cysts in corticomedullary junction

Onset adulthood
Later progression to ESRD than NHNP (presents 20s-70s)

Features:

• Polyuria & polydipsia
• Salt wasting
• Hyperuricemia- gout
• Cysts on ultrasound
• Family history of MCKD

Treatment
Confirmed by renal biopsy & genetic testing
Dialysis
Kidney transplant