Nephrology - Kidney Stones.pdf

Nephrology

[KIDNEY STONES]

Kidney stones come in a variety of forms. They’re caused by the precipitation of something - either because their quantity is large or due to decreased intravascular volume. Each type has its own risk factor, which is why th ere needs to be a close analysis of both the stone and the urine after the stone passes. The typical patient will present with colicky flank pain  that radiates to the groin  and with nausea / vomiting. This  presentation may mimic pyelonephritis (look for a fever and white cell casts) and renal cell carcinoma (look for a palpable mass).

Types of Stones Calcium Oxalate

RadioOpaque

Risk Factors ! Ca - Thiazide ! Oxalate - " Meat in diet " Citrate - ! Fruit in diet

Magnesium Ammonium Phosphate (Struvite) Uric Acid

Opaque

Alkaline Urine secondary to frequent UTIs with Urea-Splitting bacteria (Proteus)

Cysteine

Lucent

Creates Massively large stones – resection Gout - Allopurinol Tumor Lysis - Rasburicase Rare inherited rental tubular defect

Hematuria, Colicky Flank Pain Radiating to the Groin, Nausea / Vomiting

Because of the similarities between diseases, start with a urinalysis . The absence of casts and the presence of blood (even microscopic hematuria counts) is indicative of the stone. In the absence of microscopic hematuria, the likelihood of a symptomatic stone is quite low. The diagnosis is confirmed with a Non-contrasted CT scan - by far the best test. There will be times where that test is not available, as in pregnancy. If pregnant, use ultrasound. While ultrasound may not be as sensitive for distal stones or hydroureter as CT, it can be done safely without exposing the fetus to radiation. KUB  should NOT  be used for diagnosis, but can be used to track disease progression in known stone disease. Intravenous Pyelogram is no longer used.

Lucent

U/A

 Hematuria

Stone

 NonCon CT

Ø Hematuria

Consider Something Else (Highly Sensitive) U/S if Pregnant

Confirmed Stone IVF + Analgesia Treat on Size

Pass Stone Analyze Stone NOW 24-hr Urine >6 weeks later

Management is based on the size of the stone: If