Nephology

Question 1

Newborn presents with:

• bilateral renal cysts and enlarged kidneys without dysplasia.
• history of oligohydramnios and pulmonary hypoplasia
• Renal ultrasonography:
  
  • bilaterally enlarged kidneys with poor corticomedullary differentiation.
  • The renal cysts cannot be visualized on ultrasonography.

What’s the diagnosis

Answer 1

autosomal recessive polycystic kidney disease (ARPKD)

• mutations in the gene PKHD1
  
  • encodes a protein expressed in the cilia of renal tubular and hepatic bile duct epithelial cells.
• 50% chance of developing end-stage renal disease
• Associated with congenital hepatic fibrosis, abnormalities of bile ducts

Question 2

Newborn presents:

• oligohydramnios
• pulmonary hypoplasia
• renal failure
• Ultrasound: bilateral hydronephrosis
• VCUG: dilated bladder and prostatic urethra

What’s the diagnosis?

Answer 2

Posterior urethral valves

• Diagnosis: Voiding cystourethrography
• Treatment:
  
  • urinary catheter to relieve the obstruction
  • ablation of the valves
• Prognosis: Chronic kidney disease

Question 3

Gestational age nephrogenesis continues

Answer 3

until 36 weeks

Question 4

A 3.5 kg, 6-week-old boy is diagnosed with pyloric stenosis after a 3-day history of vomiting. Serum electrolytes show sodium 132 mEq/L, potassium 2.8 mEq/L, chloride 96 mEq/L, and bicarbonate 27 mEq/L. What is the most appropriate fluid to begin intravenous resuscitation for this patient?

Answer 4

Normal saline

• Prolonged vomiting loses gastric fluid rich in both hydrogen and chloride ions, resulting in both metabolic alkalosis and hypochloremia.
• most of the potassium deficit is due to urinary losses triggered by secondary hyperaldosteronism.

Question 5

when to start Na supplement in short bowel syndrome

Answer 5

Urine sodium less than 10mEq/L

less Na in distal tubles, limits ability to correct metabolic acidosis

think of contraction alkalosis, hormone: Aldosterone

Question 6

RTA with nephrocalcinosis (renal stone)

Answer 6

RTA type 1

Distal tubule, cannot secrete H+

Question 7

RTA that affect proximal tubules and cannot reabsorb HCO3

Answer 7

RTA type 2

Question 8

RTA associated with aldosterone (abnormal production or sensitivity), presents with hyperkalemia and hyperchloremia

Answer 8

RTA type IV

Question 9

It is the treatment of choice for DI in neonates

Answer 9

Hydrocholorthiazide

Why not vasopressin: difficulty in accurate dosing and variability in the absorption and action of intranasal and oral preparations- may lead to water intoxication and hyponatremia