Nephrology

Describe the characteristics of RTA type 1

• Impaired acid secre

• Metabolic acidosis, high urine pH (alkaline)

• LOW POTASSIUM, HIGH URINE CALCIUM—> nephrocalcinosis

• presents in childhood with FTT ± muscle weakness or osteopenia

• Can be caused by genetic defects, sickle cell disease, or autoimmune diseases.

Describe the characteristics of type II RTA

• PROXIMAL bicarb wasting.

• metabolic acidosis, LOW OR NORMAL potassium, often FANCONI SYNDROME

• presents in childhood with FTT, vomiting, polyurea, polydipsia, rickets

• Caused by some medications eg. aminoglycosides, heavy metal poisoning or inborn errors of metabolism such as CYSTINOSIS (most common), tyrosinemia, fructose intolerance, Wilson’s disease.

What is fanconi syndrome?

Occurs when multiple electrolytes and metabolic products are NOT getting reabsorbed by the proximal tubules in the kidney. Causes:

• Hypokalemia

• hypophosphatemia —> rickets

• aminoaciduria

• glucosuria —> polyurea, polydipsia

• FTT or short stature

What are the characteristics of type IV RTA?

• Basically aldosterone activity is impaired either because of LOW ALDO (eg. CAH, ACEI, NSAIDs) or ALDO RESISTANCE (spironolactone, UTI, CKD)

• Hyperkalemia, urine pH LOW (acidic)

What is Bartter syndrome?

Tubulopathies which present with metabolic ALKALOSIS, polyurea and polydipsia

Causes FTT

hypokalemia, metabolic alkalosis (think it acts like lasix)

What is Gitelman syndrome?

Tubulopathies which present with metabolic ALKALOSIS, polyurea and polydipsia

FTT, hypomagnesemia, metabolic alkalosis (acts like a thiazide diuretic)

What are hypertension definitions?

Use percentiles for <13 years old, use adult values for >13 years old (or if they are tall use whichever is lower)

Elevated BP: >90th% OR >120/80

Stage 1: >95th% OR >130/80

Stage 2: >95th + 12 OR >140/90

hypertensive crisis: htn + end organ damage (no cut off in peds)

What is your approach to hypertension in the office?

Elevated BP: lifestyle modification (DASH diet, exercise, normal BMI) + repeat 6 months —> 4 limp BP + repeat 6 months —> ambulatory BP + diagnostic evaluation

Stage I: lifestyle modification + repeat 1-2 weeks —> 4 limb BP + repeat 3 months —> ambulatory BP + diagnostic evaluation

Stage II: lifestyle modification + 4 limb BP + repeat 1 week —> if still at stage II start diagnostic eval and refer to subspecialist within 1 week

What are the most common causes of hypertension?

<6 years old: renal parenchymal or renovascular causes, >1 month up to 6 years is most common age group for coarctation of aorta

>6 years old: above causes or essential htn

What is included in your diagnostic evaluation for hypertension?

• Blood work: renal function, electrolytes, lipids, TSH, A1C

• Urine testing

• Renal US with doppler

• CXR

• Echo

• Eye exam

• Ambulatory BP

• Sleep study if indicated

• testing for end organ damage if indicated including CNS imaging if worried

What is the most common cause of antenatal urinary tract dilatation?

vesicoureteral reflux

What are the complex features of urinary tract dilatation?

Which children with urinary tract dilatation need referral to nephrology/urology?

• Complex features on any imaging,

• persistent or worsening postnatal UTD (persistent>10 mm after 6 months or worsening)

• maintaining postnatal CAP, and/or

• a postnatal APD >15 mm.

Which children with urinary tract dilatation need antibiotic prophylaxis?

• For high-risk patients (e.g., APD ≥15 mm or with complex features), there should be shared decision-making with the family regarding treatment with CAP, with subspecialist involvement.

• Could consider CAP for antentatal APD >10 mm UNTIL you do the post natal US (consider stopping if post-natal US is <15 mm)

Which of the children with antenatal UTD need post-natal imaging?

>7 mm on third trimester US consider repeat imaging

>10 mm on third trimester US requires follow up imaging between 2 days and 2 weeks of life, if it remains >10 then repeat in 6 months if it is >15 referral right away to specialist.

Differential for nephritic syndrome based on C3 levels and divided into systemic and renal causes (the table)

Describe the features of post-infectious glomerulonephritis

Happens AFTER the infection

hematuria, usually gross, low C3 with normal C4

C3 should normalize by 8 weeks and proteinurea should resolve once no more gross hematuria

microscopic hematuria can persist up to 1 year

Refer to nephro if Cr high, htn, C3 doesn’t recover, persistent or nephrotic range proteinuria

Compare IgA nephropathy and PIGN

in PIGN C3 should NORMALIZE BY 8 weeks

What are the characteristics of alport syndrome?

• X-linked mutation (but females also affected due to chimerization)

• Renal features: intermittent gross hematuria on background of microscopic, proteinuria late finding, progressive renal failure

• Extra-renal features: early onset SNHL, anterior lenticonus

• Treat with ACEI, eventually needing renal replacement/transplant

What is nephrotic range proteinuria?

3+ on dipstick

>200 mg/mmol

What are the red flags in nephrotic syndrome?

What are the complications of nephrotic syndrome?

• fluid overload and electrolyte abnormalities

• clots

• infections including spontaneous bacterial peritonitis (indication for extended pneumococcal vaccine)

• dyslipidemia

How much compensation do you expect with:

• metabolic acidosis

• metabolic alkalosis

• respiratory acidosis

• respiratory alkalosis

Metabolic changes HCO3:CO2

• acidosis 1:1

• alkalosis 1:0.7

Respiratory changes 1/2/4/5 rule (see photo)

What are the characteristics of Cystinosis?

• Autosomal recessive lysosomal storage disease

• Features: corneal cysteine crystals, hypothyroidism, excessive thirst, Fanconi syndrome, Rickets, FTT

• Treat with cysteamine

What is the definition of AKI?

Cr increase 1.5x baseline OR UO <0.5 ml/kg/hr over 6-12h

What is MCDK

Multi-cystic dysplastic kidney

Congenital, non‑functional kidney replaced by multiple non‑communicating cysts

usually not genetic

usually unilateral with affected kidney non-functional and it involutes over time

What is PCKD

polycystic kidney disease

genetic disease causing progressive formation of corticol and medullary cysts

enlarged kidney at birth, usually bilateral

Hematuria, proteinuria (mild), progressive decline in GFR —> ESRD