Acute Kidney Injury

___ days
-- CC:
(low PO intake, NSAID use, new meds, change in urinary habits (nocturia, incontinence, frequency, dysuria, retention, straining), hematuria, recent contrast, infection)
-- (sudden / gradual) onset,
-- (constant / intermittent) course
-- progressively (worsening / improving / unchanged) symptoms.
-- Associated symptoms:
dec UO, fatigue, weakness, dyspnea (volume overload), edema, decreased appetite,
-- Pertinent negatives:
denies fever/chills, no flank pain, using nephrotoxic meds , urinary retention symptoms (hesitancy or straining, frequency, Urgency, Nocturia, incontinence)
-- Pertinent Exam:
mucous membranes (dry), JVP (low vs elevated), lung exam (clear vs crackles), cardiac exam, peripheral edema, abdominal exam (distension, bladder fullness), CVA tenderness (if pyelo/obstruction), skin (rash—AIN)
-- Pertinent Data:
baseline BUN/creatinine, CBC, BMP (BUN/Cr ratio often >20 prerenal), Mag, Phos, LFTs, UA (Hyaline cast -> prerenal, ATN-> Muddy brown , GN->RBC cast ,AIN->WBC casts ) FeNa (<1% pre-renal, >2% ATN) Less specific in CKD and diuretic use, or FEUrea <35% (if on diuretics suggest pre-renal) Urine-Na (> 40 suggests ATN and UNa < 20 suggests pre-renal), Urine Cr, serum CK if c/f rhabdo, renal US vs CTAP** if c/f obstruction suspected
-- Pertinent PMH/SH/FH:
CKD, CHF, cirrhosis, malignancy
Pertinent Home meds:
(NSAIDs, ACE/ARB, abx, anticholinergics, PPI, allopurinol)

-- meeting criteria : ↑ Creatinine ≥ 0.3 mg/dL in 48 hours or ↑ Creatinine ≥ 1.5× baseline within 7 days or Urine output < 0.5 mL/kg/hr for 6 hours
-- DDX:
- Pre-Renal - hypovolemia, dehydration, decreased effective volume with CHF/cirrhosis, shock, change in renal dynamics with NSAIDs, ACEi/ARB;
- Intrinsic - ATN MC (socks/toxins, muddy brown casts), then GN (Immune-mediated, post-infectious,RBC casts + protein), AIN (NSAIDs, PPIs, antibiotics, ifx, Fever + rash + eosinophilia, WBC casts) vascular;
- Post-Renal - retention, obstruction (BPH, stones, tumors),
- Can't Miss DDX: Glomerulonephritis - tea-colored urine; Vasculitis - rash, hemoptysis, arthritis, h/o autoimmune dx; Rhabdo (cause of ATN) - found down, seizure, muscle pain, proximal muscle weakness; AIN - new meds (NSAIDs, beta-lactams, sulfa, PPI, allopurinol); Complex Obstruction - cancer*

— Hospital course to date:

Plan:
-- f/u FeNa or FEUrea, Urine-Na, Urine Cr
-- trend electrolytes and replete
-- 500cc-1L IV fluid challenge if suspected to be prerenal (( If Cr improves to baseline in <48H then was likely pre-renal ))
-- 1/2 L LR -> 125 ml/hr (prerenal)
-- daily BUN, Creatinine, and BMP for hyperK, hyperPhos, acidosis, uremia
-- strict I/O,
-- avoid nephrotoxoc agents: NSAIDs, ACE/ARB, diuretics
-- if c/f Post-Renal etiology - place foley, give alpha-antagonists (tamsulosin) or 5-alpha-reductase inhibitors if BPH; perc nephrostomy if malignant obstruction
-- Nephrology consult for RRT (AEIOU)

-- if c/f AIN - stop the offending agent (NSAIDs, PPIs, antibiotics) Nephrology consult , pred 40-60mg daily for 1-2 weeks
-- ATN - Supportive care ONLY Optimize perfusion
-- c/f Glomerulonephritis Nephrology consult, Steroids (first-line in many GN) ± immunosuppressants