Renal & Acid-Base confusion pairs
15 Renal & Acid-Base topics students commonly mix up on Step 2 CK, each with the fastest separator, a side-by-side comparison, and a free practice question.
Step 2 CK pairs are in open beta while clinical review finishes. Spot an issue? Tell us.
- Type 1 RTA vs Type 2 RTAUrine pH remaining above 5.5 during metabolic acidosis identifies type 1 RTA.
- Type 4 RTA vs Other RTAsHyperkalemia in a normal anion gap metabolic acidosis identifies type 4 RTA until proven otherwise.
- Prerenal AKI vs Intrinsic AKIUrine sediment with muddy brown granular casts is the fastest discriminator for intrinsic AKI.
- Postrenal AKI vs Intrinsic AKIHydronephrosis on renal ultrasound is the fastest branch point toward postrenal AKI.
- Hyperkalemia management vs Hypokalemia managementECG instability in hyperkalemia is the immediate branch that mandates IV calcium first.
- Hyponatremia hypovolemic vs Hyponatremia euvolemic (SIADH)Volume exam showing hypovolemia versus euvolemia.
- Pyelonephritis vs CystitisFever with flank tenderness separates pyelonephritis from lower-tract cystitis.
- AIN vs ATNWhite blood cell casts after a recent culprit drug favor AIN, while muddy brown granular casts favor ATN.
- Nephritic syndrome vs Nephrotic syndromeRed blood cell casts on urine microscopy identify nephritic syndrome rather than nephrotic syndrome.
- Anion gap metabolic acidosis vs Non-anion gap metabolic acidosisAnion gap elevation above normal is the primary branch point between these two metabolic acidoses.
- Central DI vs Nephrogenic DIUrine osmolality response to desmopressin separates central from nephrogenic diabetes insipidus.
- SIADH vs Cerebral salt wastingClinical hypovolemia in a hyponatremic neurologic patient points to cerebral salt wasting rather than SIADH.
- Calcium oxalate stone vs Uric acid stonePersistently acidic urine pH below 5.5 with rhomboid crystals points to uric acid stone.
- Pyelonephritis vs Papillary necrosisImaging evidence of sloughed or cavitated renal papillae is the decisive discriminator for papillary necrosis.
- Struvite stone vs Cystine stoneAlkaline urine with urease-positive infection points to struvite, while hexagonal crystals point to cystine.