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eGFR
- CKD-EPI 2021 race-free preferred
- Cystatin C: muscle mass independent
- < 60 = CKD (if persistent ⥠3 mo)
- Cockcroft-Gault still used for drug dosing
UACR
- A1 < 30 mg/g (normal)
- A2 30-300 mg/g (microalbuminuria)
- A3 > 300 mg/g (macroalbuminuria)
Nephrotic vs Nephritic
| Proteinuria |
> 3.5 g/24h |
Variable |
| Hematuria |
Variable |
Common, RBC casts |
| Edema |
Severe |
Mild-moderate |
| HTN |
Less common |
Common |
| AKI |
Less common |
Common |
| Hypoalbuminemia |
Yes |
Variable |
| Hyperlipidemia |
Yes |
No |
Urine Casts
- Hyaline: normal
- RBC: glomerular
- WBC: pyelonephritis, AIN
- Muddy brown granular: ATN
- Waxy: chronic
- Fatty: nephrotic
Electrolyte Quick Differential
- Hyponatremia: SIADH, cirrhosis, HF, hypothyroid, adrenal
- Hyperkalemia: AKI, CKD, ACE/ARB, RTA-IV
- Hypocalcemia: hypoPTH, CKD, vit D def, hypomagnesemia
- Hypophosphatemia: refeeding, alcohol, hyperPTH
Anion Gap (MUDPILES)
- Methanol
- Uremia
- DKA
- Paraldehyde
- Iron, INH
- Lactic
- Ethylene glycol
- Salicylates
Glomerular vs Non-Glomerular Hematuria
- Glomerular: dysmorphic RBC, RBC casts, proteinuria
- Non-glomerular: normomorphic RBC, no casts, less proteinuria; stones, infection, tumor
ææ··æ·æ¯èŒ
| Glomerular |
RBC, dysmorphic RBC |
GN, vasculitis |
| Tubular (ATN) |
Muddy brown granular |
Ischemia, toxin |
| Interstitial |
WBC, eosinophils |
AIN, infection |
| UTI / pyelonephritis |
WBC casts |
Infection |
| Chronic kidney disease |
Waxy |
Long-term |
| Nephrotic |
Fatty (oval fat bodies) |
Heavy proteinuria |
Special Topics
Race-Free eGFR 2021
- Removed Black race coefficient
- More equitable; less likely to under-diagnose CKD in Black patients
- Combined Cr + cystatin C even better
APOL1 Risk Variants
- G1, G2 variants
- African ancestry
- â Risk: FSGS, HIV-associated nephropathy, lupus nephritis, hypertensive nephropathy
- Genetic counseling
Cystatin C
- Constitutive expression by nucleated cells
- Less affected by muscle mass
- More accurate in elderly, athletes, malnourished