Table of contents
Approach to Hematuria
- Determine if cause is glomerular or non-glomerular by looking at urinalysis, urine microscopy (dysmorphic cells, RBC casts, etc.)
- Glomerular --> continue workup, labs, consider renal biopsy
- Non-Glomerular --> Needs upper & lower tract assessment
- Cystoscopy --> upper tract
- CT urogram --> lower tract
Maintenance
- How much to give?
- 4-2-1 Rule
- 4 mL/kg/h for first 10kg or less
- 2 mL/kg/h for next 10kg
- 1 mL/kg/h for remainting kg
- Example. 3kg infant (12mL/h), 25kg child: 4x10+2x10+1x5=65 mL/hr
- Ask Ins/Outs.
- 4-2-1 Rule
- Which Fluid to give?
- Before starting IV fluids, check electrolytes (Na, K, glucose, urea, creat).
- Monitor lytes daily if >50% maintenance fluid via IV.
- Start with NS or RL. Then depends on Na
- [Na+] <138 mmol/L, continue RL or NS
- [Na+] 138-144 mmol/L, use 1/2 NS, NS, or RL (IV solution with [Na+] 77-135
- [Na+] 145-154 mmol/L, use 1/2 NS ([Na+] ~77)
- [Na+] >154 mmol/L (Hypernatremia)
- Risk of cerebral edema with rapid rehydration.
- Correct slowly. Use formulas to determine Na deficit and rate of correction. (TODO)
Urine Lytes
- Urine Osmolality
- If <200 --> ADH is OFF (dilute urine)
- If >200 --> ADH is ON (urine concentrated)
- Urine Sodium
- if < 20 --> Aldosterone effective (absorbing Na and water)
- If > 40 --> Aldosterone NOT effective (losiing Na in kideys) Renal failure, etc..
- Urine Chloride
- If High --> Hyperaldosteronism
- If Low --> Vomiting, Diarrhea
Chronic Kidney Disease
Hypertension
- Managing hypertension is indicated for all patients with kidney disease. (regardless of etiology)
- Controlling blood pressure helps to decrease cardiovascular risk and may help to prevent progression to end-stage kidney disease.
- ACEi/ARB are preferred Anti-HTN agents in CKD, especially in those with proteinuria.
- Mechanism:
- ACEi/ARB lower efferent arteriolar resistance and lower intraglomerular pressure.
- The lower intraglomerular pressure is thought to be protective for the kidney but may be associated with a slight increase in the serum creatinine level (30% increase is acceptable).
- CAUTION: Use of these agents also may cause hyperkalemia. Use diuretics to manage hyperkalemia, further HTN, and edema.
- Higher doses of diuretics are often required.
GFR Estimation
- Ways to estimate:
- Modification of Diet in Renal Disease (MDRD) study
- Underestimates GFR at higher (normal) values.
- If calculated eGFR is >60 mL/min/1.73m^2 then report as 60.
- Study included patients with CKD with lower muscle mass than general population.
- Underestimates GFR in healthy, low-risk persons with normal/increased muscle mass.
- Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI)
- Reduced bias associated with MDRD, shown in NHANES study.
- NHANES: median eGFR was 94.5 mL/min/1.73m^2 using CKD-EPI and 85 using MDRD.
- Some patients Stage 3 CKD via MDRD and no CKD by CKD-EPI.
- Reduced bias associated with MDRD, shown in NHANES study.
- Cockcroft-Gault
- Underestimates GFR at higher values.
- Less accurate than MDRD and CKD-EPI?
- 24-hour urine collection - for Creat Clearance.
- Good but inaccurate due to difficulty in collecting 24-hr urine sample.
- Undercollection = inaccurate GFR.
- Radionucleotide kidney clearance scanning
- Very accurate, but more invasive and expensive than eGFR.
- Often used in evaluating live kidney donors.
- Modification of Diet in Renal Disease (MDRD) study
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CKD Stage GFR level (mL/min/1.73 m2) Stage 1 ≥ 90 Stage 2 60 - 89 Stage 3 30 - 59 Stage 4 15 - 29 Stage 5 < 15
Nephrotic Syndrome
- 24-hr urine proteinuria
- Normal < 150 mg/day
- Nephrotic Range >3.5g/day
- Workup (causes)
- Serology: ANA, C3/4, SPEP, UPEP, syphilis, HepB, cryoglobulins
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