Presentation on theme: "Darrell Gray, II MD Internal Medicine Tenwek Hospital"— Presentation transcript:
1 Darrell Gray, II MD Internal Medicine Tenwek Hospital Acute Renal FailureDarrell Gray, II MDInternal MedicineTenwek Hospital
2 Case #154yo M with AIDS (CD4 of 39) who presents to Tenwek with altered mental status and neurologic deficits. You do a thorough work-up but discover that you need to obtain a CT scan w/ contrast. His baseline creatinine is 1.4, but he returns from the CT scan and now has creatinine of 2.5, with decreased urine output.
3 Case #242yo F with no significant PMH presents to CCC c/o 4 days of nausea, vomiting and diarrhea, with fever to 101OF. She has been unable to keep any food down, and very little in the way of liquids. Her son is in primary school and had similar symptoms 1 week ago. Creatinine is Last one was 0.9 about a year ago.
4 Case #375yo M with h/o prostate cancer diagnosed in It was metastatic to his ribs at the time, so he was not a candidate for prostatectomy. He has done well since then on hormone therapy in Nairobi, but presents to clinic today c/o abdominal pain and decreased urine output over the last 5 days, as well as irritability and back pain. His creatinine is 8.5, up from a baseline of 1.4.
5 How does it apply to you?No matter what specialty you go into, you need to understand the kidneysSurgery – post-operative renal failureOB – proteinuria, ureteral reflux, pre-eclampsia, pyeloPeds – ARF, HUS, polycystic kidney dz, minimal changeRadiology – contrast-induced ARF (what creatinine is safe to give contrast?), nephrogenic fibrosing dermopathy, RAS (dx on angiogram or MRI)ENT – sinus disease and its connection with pulmonary/renal syndromes like Wegener’sPathology – identify underlying disease process
6 Definitions Increase in serum creatinine (1mg/dL = 88.4umol/L) By > 0.5mg/dL in < 2 weeks timeOR, > 20% increase if baseline creatinine is > 2.5mg/dLPoor urine outputOliguria ( mL in 24hrs)Anuria (<100mL in 24hrs)
7 Tell me more about creatinine An indirect marker of renal functionIs not elevated in early stages of kidney diseaseWill not be raised above normal level until 60% loss of kidney functionShould be used to calculate the creatinine clearance for a more direct estimation of renal functionA small, elderly person may have a totally “normal” creatinine but a decreased creatinine clearanceClearance declines predictably with ageIt’s reflective of underlying muscle mass, which is why it can be deceptively “normal” in the elderly
8 Causes of deterioration in renal function 3 major categories:Pre-renalIntrinsic renalPost-renalLet’s go through each one…
9 Pre-renal Characterized by decreased blood flow to the kidneys Common causes:Hypovolemia – ↑ losses, ↓ intake, diuresisHypotension – from vasodilation (sepsis, anaphylaxis, BP meds), poor cardiac output (heart failure; can actually be volume overloaded)ACE inhibitors or ARBs – alterations in efferent arteriolar constriction change renal blood flow (RBF)NSAIDs – afferent arteriolar constriction ↓ RBFRenovascular – renal artery stenosis, fibromuscular dysplasia, hepatorenal syndrome
10 Intrinsic Renal Damage to the kidney itself Important causes: Acute Tubular Necrosis (ATN) – contrast dye, severe hypotension (shock)Acute Interstitial Nephritis (AIN) – medications (PCNs, sulfa drugs, NSAIDs)Glomerular disease – numerous causes, including post-strep glomerulonephritis, vasculitis (like Wegeners), lupus nephritis, HIV, and other entities like minimal change disease, FSGS, etc.Microvascular thrombosis – TTP, HUS, etc.Embolic – cholesterol emboli (post-cath)Infectious / depositional – pyelonephritis, nephrocalcinosis
11 Post-renal Obstruction of ureter, bladder outlet, or of urethra causes backup of urine and hydronephrosisCommon causes:Bladder neck – BPH, prostate Ca, neurogenic bladder, anticholinergic medsUreteral obstruction – lymphadenopathy, malignancy, nephrolithiasisTubular – crystal precipitation
13 How do I apply this to my patient? History and physicalDehydration, fevers, vomiting or diarrhea, change in urine output, SOB, Edema, recent procedures, medications??Vital signs, signs of dehydration, skin rash??Laboratory dataUrinalysis w/ microscopic analysis, creatinine clearance, urine electrolytes, serology (if suspecting autoimmune process or vasculitis)ImagingRenal US or CT, bladder scan
14 High Yield Test Interpretation Urinalysis – a wealth of information!Components:Specific gravity – tells you about dilution or concentration of urine (dehydration?)Protein – points towards damaged machinery (nephrotic syndrome? Lupus? )Glucose – glucose diuresis?Ketones – DKA? Not eating/drinking?Blood / RBCs – kidney stone? Glomerular disease?Nitrite – UTI?Leukocyte esterase – UTI?WBCs – UTI? Pyelo?Bacteria – UTI?
15 High Yield Test Interpretation Urine microscopyUnder-appreciated and under-utilizedCan give you incredibly valuable information about underlying processesAnalysis of “casts”“Sediment”Bland = no significant castsActive = red cell casts, white cell casts, “muddy brown” or granular castsHyaline casts = often pre-renal, or CKD (“waxy casts”)Can point towards pyelo (white cell casts), glomerulonephritis (red cell casts)
16 = pre-renal cause (usually) CastsHyaline= pre-renal cause (usually)Granular, “muddy brown”= acute tubular necrosis!
17 High Yield Test Interpretation ChemistryBUN : Cr ratio – if >20:1, is strongly suggestive of pre-renal azotemiaUrine sodium and creatinineAllows you to calculate the fractional excretion of sodium (FeNa)If < 1%, this is c/w pre-renal causeIf >2%, this is c/w intrinsic renal causeUrine ureaUseful when patients on diuretics to calculate FeUrea<35% suggests pre-renal cause
18 High Yield Test Interpretation Urine eosinophilsVery specific for acute interstitial nephritisBladder scanA rudimentary ultrasound device that gives a mL reading of urinary bladder contentHave patient void, then scan bladder, or insert foley and record “post-void residual” volume if no machineHigh post-void residual is suggestive of prostatism or neurogenic bladderIf > mL, data show risk of UTI is increasedIf VERY high ( mL), is clearly c/w post-renal cause
19 Treatment by Cause Pre-renal Intrinsic renal Volume expansion Normal saline, to enhance renal perfusion (or LR)Follow chemistry (BUN, creatinine), urine outputHold BP meds to ensure good renal perfusion (within reason)Intrinsic renalIf AIN, stop potentially offending agentOr, if active sediment, consider special studies (lupus labs, ANCA for vasculitis, etc)Supportive care, especially for ATNWatch lytes, UOP (beware post-ATN diuresis!)Biopsy as last resort, if indicated
20 Treatment by Cause (cont’d) Post-renalFoley placement! (if you can; sometimes it’s not so easy)Follow BUN, creatinineShould improve slowly over several daysIf not improved, consider abdominal imaging for mass lesion compressing bladder outlet, ureters, etc.
21 Don’t forget to . . . Hold nephrotoxic meds Renally dose the meds Stop ACE inhibitor / ARB – these can be harmful in acute renal failureNo NSAIDsRenally dose the medsCan have catastrophic consequencesExample: morphine has a toxic, renally cleared metabolite, morphine 6-glucoronide; can cause seizures in ARFLots of medicines need to be re-dosed (antibiotics like cipro or Keflex or Zosyn or Vanc, zantac, neurontin, atenolol, lovenox, etc.)
22 When to Start Dialysis? At what creatinine should you begin HD? Trick question; creatinine doesn’t matterAn easy acronym: AEIOUAcidosis – metabolicElectrolytes – hyperkalemiaIntoxication – if dialyzable (lithium…)Overload – pulmonary edema, CHF…Uremia – pericarditis, “frost,” AMS
24 Case #154yo M with AIDS (CD4 of 39) who presents to Tenwek with altered mental status and neurologic deficits. You do a thorough work-up but discover that you need to obtain a CT scan w/ contrast. His baseline creatinine is 1.4, but he returns from the CT scan and now has creatinine of 2.5, with decreased urine output.
25 Questions Is this renal failure? What type is it most likely to be? What tests might you order?How would you manage this?Answers: Yes, ATN from contrast, urine microscopy to look for “muddy brown” / granular casts, supportive careBonus: how might you have prevented this? (intern level)Pre-hydration and N-acetylcystine (Mucomyst) prophylaxis
26 Case #242yo F with no significant PMH presents to CCC c/o 4 days of nausea, vomiting and diarrhea, with fever to 101OF. She has been unable to keep any food down, and very little in the way of liquids. Her son is in primary school and had similar symptoms 1 week ago. Creatinine is Last one was 0.9 about a year ago.
27 Questions Is this renal failure? What type is it most likely to be? What tests might you order?How would you manage this?Answers:Yespre-renal from dehydration / volume depletionOrthostatic vitals, BUN:Cr ratio, FeNaGive fluids (saline saline saline!), follow creatinine
28 Case #375yo M with h/o prostate cancer diagnosed in It was metastatic to his ribs at the time, so he was not a candidate for prostatectomy. He has done well since then on hormone therapy in Nairobi, but presents to clinic today c/o abdominal pain and decreased urine output over the last 5 days, as well as irritability and back pain. His creatinine is 8.5, up from a baseline of 1.4.
29 Questions Is this renal failure? What type is it most likely to be? What tests might you order?How would you manage this?Answers:YesPost-renal, from prostatic obstructionBladder scan or post-void residual; renal ultrasoundFoley placement, give fluids, follow UOP and creatinine