Question | Answer |
90% of stones are: | radiopaque (visible): Ca & struvite). Uric acid & cystine stones are radiolucent. |
Calcium oxalate or Ca phosphate stones | 75%; occasionally with chronic hypercalcemia (hyperparathyroidism) |
Magnesium – ammonium – phosphate (struvite) stones: prevalence | 10-15% |
Uric Acid / cystine stones: prevalence (%) | Uric Acid 5-8% of all kidney stones. Cystine 1-3% |
Stones: DDx | AAA; Appendicitis; Tuboovarian Abscess (TOA); Ectopic Pregnancy |
Urolithiasis: dx imaging | noncontrast CT (high sensitivity); US (hydronephrosis; good for PG); KUB (less specific) |
Urolithiasis admission criteria | Infection / Sepsis; Complete Obstruction; Deteriorating renal fn; Intractable N/V; Solitary kidney; Very large or proximal stones |
Renal stones lodge at: | UPJ (kidney stones), ureterovesicular junction/UVJ (bladder stones), or ureter at level of iliac vessels |
Urolithiasis RFs | Prior stones, FH, low Ca/fluid intake, high oxalate/pro/Na intake, gastric bypass (RYGB); gout, DM, obesity, chronic UTIs, chronic diarrhea |
Struvite stones form in pts with: | recurrent UTI (urease forming bacteria: proteus / klebsiella). Staghorn: often struvite |
Urolithiasis clinical features | colicky flank pain +/- hematuria +/- fever/chills, N/V |
Symptoms of renal stone in upper ureter: | radiate to anterior abdomen |
Symptoms of renal stone in lower ureter: | radiate to ipsilateral groin, testes/ labia |
Symptoms of renal stone in UVJ: | urgency, frequency, pelvic pain |
ADPKD comorbididities | Berry aneurysms of the circle of Willis; cerebellar hemangioblastomas; hepatic cyst; hypertension (<50% of pts); valvular heart dz; divertic; renal failure |
Meds contributing to stone formation | Antacids, carbonic anhydrase inhibitors (raise urine pH). Loop diuretics (increase urine Ca concentrations), thiazides (uric acid stones). Large doses vitamin C (-> hyperoxaluria) |
Dietary factors on stone formation | Animal protein metabolism -> metabolic acidosis -> more Ca filtered/hypercaliuria. Meat (purine) -> uric acid. Green leafy (oxalate) -> Ca oxalate stones |
Secondary causes of stones | HyperPTH, hyperthyroid, Cushing, granulomatous (sarcoid/TB/dissem candida), immobility, vit D intox, bone dz |
Kidney stone dx | Stone analysis to ID. Noncontrast CT is TOC. US can show obstruction & hydro. 24hr urine, Urine Ca:Cr ratio. Check PTH in chronic pt if Ca elevated. |
Kidney stone mgmt | IV fluids, analgesia. Most <5mm stones pass spontaneously. 5-10mm may need removal. Diet to lower Ca/ oxalate |
UA findings in stones | pH <5.0 = uric acid & cystine. pH > 7.2 = struvite |
Stones removed by: | lithotripsy (ESWL) or ureteroscopy w/extraction. Stones >10mm may require admission for lithotripsy or percutaneous nephrolithotomy |
Medullary sponge kidney characteristics | Benign. Hereditary AD: MCKD1 or MCKD2 mutation on chromosomes 1 & 16. Dx in 4th-5th decade. |
ADPKD genetics | Chromosome 16 short arm defect (90%). Chromosome 4 (10-15%), slower w/longer life expectancy |
Epithelium-lined cavities filled with fluid or semisolid that develop from renal tubular elements = | cysts (70% of all renal masses) |
Dx study for medullary sponge kidney | Intravenous pyelogram (IVP) - will show striations in papillary portions (=contrast accumulation in dilated collecting ducts) |
Large echogenic kidneys on US = | ADPKD |