Nephrolithiasis and PCKD

Question 1

Nephrolithiasis

Answer 1

Renal calculi. Stones are most commonly calcium oxalate, but many other types exist.

Risk factors are:

1) positive family hx
2) low fluid intake
3) gout
4) meds (allopurinol, chemo, loop diuretics)
5) postcolectomy/postileostomy
6) specific enzyme deficiencies
7) type 1 RTA (due to alkaline urinary pH and associated hypocitruria)
8) hyperparathyroidism

Most common in older males

Question 2

history and exam for kidney stones

Answer 2

1) presents with acute onset of severe, colicky flank pain that may radiate to the testes or vulva and is associated with nausea and vomit
2) Patients are unable to get comfortable and shift position frequently (as opposed to those with peritonitis who lie still)

Question 3

Dx of kidney stones

Answer 3

1) UA may show gross or micro hematuria (85%) and an altered urine pH
2) Noncontrast abdominal CT is gold standard for dx. However, plain AXRs are still useful
3) US is preferred for pregnant patients and kids
4) KUB identifies radiopaque stones but will often miss stones that are radiolucent
5) IVP is rarely used

Question 4

Which bacteria are associated with staghorn calculi?

Answer 4

Urease producing organisms like Proteus

Question 5

Calcium oxalate/calcium phosphate stones

Answer 5

83% of cases

1) Info: Most common causes are idiopathic hypercalciuria* and primary hyperparathyroidism. Alkaline urine. Radiopaque
2) Tx: Hydration, dietary sodium and protein restriction, thiazides. Do not lower calcium intake (can lead to hyperoxaluria and an increased risk of osteoporosis)

Question 6

Struvite (Mg-NH4-PO4) or “triple phosphate” stones

Answer 6

9% of cases

1) Info: Associated with urease producing organisms. Form staghorn calculi. Alkaline urine. Radiopaque
2) Tx: Hydration; treat UTI if there. Surgical removal of staghorn stone

Question 7

Uric acid stone

Answer 7

7% of cases

1) Info: Associated with gout, xanthine oxidase deficiency and high purine turnover states (chemo). Acidic urine (pH less than 5.5). Radiolucent* on plain film, but detectable with CT
2) Tx: Hydration; alkalinize urine with citrate, which is converted to HCO3 in the liver; dietary purine restriction and allopurinol.

Question 8

Cystine stones

Answer 8

1% of cases

1) Info: Due to a defect in renal transport of certain amino acids (COLA - cystine, ornithine, lysine, arginine). Hexagonal crystals.* Positive urinary cyanide nitroprusside test.* Radiopaque.
2) Tx: Hydration, dietary sodium restriction, alkalinization of urine, penicillamine

Question 9

Treatment of kidney stones

Answer 9

1) Hydration and analgesia* are initial tx
2) Kidney stones less than 5mm in diameter can pass through urethra; stones 0.5 to 3cm can be treated with extracorporeal shockwave lithotripsy (ESWL), percutaneous nephrolithotomy or retrograde ureteroscopy
3) preventative measures include hydration* and dietary changes
4) Dietary changes to prevent calcium stones include increasing fluid intake (most important), increased calcium intake*, less dietary protein/oxalate intake, and less sodium intake.

Question 10

PCKD

Answer 10

Characterized by presence of progressive cystic dilation of the renal tubules, as well as by cysts in the spleen, liver, and pancreas.

Question 11

ADPKD

Answer 11

1) Most common
2) Usually ASx until patients are over 30
3) One half of ADPKD patients will have ESRD requiring dialysis by age 60
4) Associated with higher risk of cerebral aneurysm, especially in patients with positive family hx

Question 12

ARPKD

Answer 12

Less common but more severe. Presents in infants and young children with renal failure, liver fibrosis and portal HTN. may lead to death in first few years of life

Question 13

History and exam for PKD

Answer 13

1) Pain and hematuria are the most common presenting symptoms. Sharp, localized pain may result from cyst rupture, infection, or passage of renal calculi
2) Additional findings include HTN, hepatic cysts, cerebral berry aneurysms,* diverticulosis, and MVP
3) Patients may have large, palpable kidneys on abdominal exam

If patient with known ADPKD develops sudden-onset severe HA you MUST rule out SAH from a ruptured berry aneurysm

Question 14

Dx of PKD

Answer 14

Based on US or CT. Multiple bilateral cysts will be present throughout the renal parenchyma, and renal enlargement will be seen. Genetic testing by DNA linkage analysis or ADPKD1 and ADPKD2 is available.

Question 15

Tx of PKD

Answer 15

1) Prevent complications and lower rate of progression to ESRD. Early management of UTIs is critical to prevent renal cyst infection. BP control (ACEIs, ARBs) is needed to lower HTN-induced renal damage
2) Dialysis and renal transplant are used to manage patients with ESRD