8/8/2012

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Kidney…Fun and Failure

Tom Ozbirn, M.D.

General Session 2, Saturday, 9/8/12

9:30 a.m. to 11:30 a.m.

Thomas W. Ozbirn, Jr DO, FACP

Nephrology Associates, PC

Birmingham, Alabama

8/8/2012

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Objectives

• Understand Categories of

AKI

CKD

ESRD

• Navigate confusing nomenclature of renal disease

• Understand basic renal function

• Understand consequences of loss of renal function

• Key coding issues

Case 1

72 year old man admitted: recurrent CHF, CKD 4 ( Cr 3 ) and hypertension

• PMH

DM x 16 years

HTN, severe, x 10 years

CKD with rising creatinine past years

AAA, repaired 8 years ago

Coronary Artery Ds, sp MI 2 years ago

Data

• Chest X-Ray- CHF

• Urinalysis- 1+ protein

• Echocardiogram- normal LV function

• Renal Ultrasound- Rt kidney 7 cm, L kidney 10 cm

• MRA- occluded L renal artery, severe stenosis Rt renal artery

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PTRA of Rt Renal Artery

• Brisk Urine output

• CHF resolution

• Blood pressure falls

• Creatinine falls 1.8

What is principal Diagnosis?

• CHF

• Hypertension with CKD

• Hypertension with CHF and CKD

• Atherosclerosis of Renal Artery

Anatomy of Kidney

• Gross Features – Paired retroperitoneal organs – Upper pole opposite 12th thoracic vertebrae – 11-12 cm in length – Single renal artery – Cortex and medulla

• Nephron – Afferent/efferent arterioles – PT – 60-70% A–II CAI – Loop of Henle – 20-25% flow loop – Distal tubule 5% flow - Thiazide – Collecting duct 4% aldo, ADH, K+ sparing

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Renal Function and Disorders of Water and Sodium Balance

• Overview – 50-60% BW

– 2/3 intracellular, 1/3 extracellular

– Body compartment electrolytes • Sodium – extracellular

• Potassium – intracellular

• Osmolarity – Different solutes but equal concentration

– H2O moves to compartment with higher solute

– 2 X sodium + glu/18 + BUN/2.8

– Osmolar gap = EtoH, Methanol, Ethylene glycol

Introduction

• CKD is a worldwide public health problem

-Rising incidence and prevalence

-In 2003, 100,499 patients entered ESRD programs and 82,000 died

-Disproportionate share of healthcare resources

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Introduction

-Survival probability at 1,5,10 years is 80,40 and 18%

-Growth due to changes in demographics

-Difference in disease burden between racial

groups

-Under recognition of early stages

-”Under diagnosed”

Stages of CKD

• Stage 1- Albuminuria, normal GFR

• Stage 2- Albuminuria, GFR 60-90

• Stage 3- GFR 30-59

• Stage 4- GFR 15-29

• Stage 5- GFR < 15 or ESRD

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Prevalence

• Presence of markers of kidney damage for > 3 months

• Presence of GFR < 60 ml/min for 3 months

• Elevated serum creatinine

-0.8 to 1.3 in men

-0.6 to 1.0 in women

Decreased GFR

-Cockcroft-Gualt

-MDRD

Racial Variations

• Racial and ethnic differences in ESRD

• 256 per million population in whites

• 982 per million population in African Americans

• 344 per million in Asian Americans

• 514 per million in Native Americans

• Age/gender ratio (AA/white) 6 to 1

Impact of CKD on Morbidity

• HTN, DM, CVD and PVD present in far greater proportion

• 3x increase in hospital days

• Older age, gender, race, cardiac disease and PVD are risk factors for hospitalization

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Management of CKD

• Natural history

-Initial injury from hematuria to renal failure

-Post infectious GN- recover with little to no sequelae

-Lupus nephritis-repeated insults and progression

Management

• Adaptive hyperfiltration

-Initially beneficial

-Progressive renal insufficiency

-Uremia

-ACEi may slow progression

-Rate of progression varies

Association with CVD

• CKD is a risk factor for CVD

• Risk of death from CVD greater than the risk of ESRD

• Phosphate binders may increase Coronary Atherosclerosis

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Progression of CKD

• Intraglomerular HTN

• Glomerular hypertrophy

• Hyperlipidemia

• Metabolic Acidosis

• Tubulointerstitial disease

• Secondary FSGS

Progression of CKD

• ACEi/ARB

• Antihypertensive therapy given for renal and cardiac protection

• Reduced proteinuria

• Goal systolic BP 110

• Therapy more effective in earlier stages

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Progression of CKD

• Hyperlipidemia

• Metabolic Acidosis

• Protein restriction

• Smoking cessation

• JNC 7/ K/DOQI guidelines

Treatment of Complications

• Volume overload

-Homeostatic mechanisms until GFR<15

-Less able to respond to rapid infusions of sodium

-Sodium restriction

-Diuretics

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Treatment of Complications

• Hyperkalemia

-Aldosterone secretion and distal flow

-Oliguric, increase K+ diet, increased tissue breakdown

Metabolic Acidosis

-Hydrogen ion retention

-Serum bicarbonate rarely <10

Treatment of Complications

• Hyperphosphatemia

-Reduce filtered phosphate load

-Secondary Hyperparathyroidism

-Dietary phosphate restriction

-Protein restriction

-Phosphate binders

-CaxPO4 <55

Treatment of Complications

• Renal Osteodystrophy

-Osteitis Fibrosa

-Osteomalacia

-Adynamic Bone Disease

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Treatment of Complications

• Hypertension

-80-85% of patients with CKD

-Diuretics

-Loop vs. Thiazides (less effective if GFR < 20)

Sexual Dysfuntion

-Amenorrhea common

-50% of men with ED

Treatment of Complications

• Anemia

-Normocytic and Normochromic

-Reduced production of Erythropoetin

-Shortened RBC survival

-Untreated, Hct stabilizes at 25

-CHOIR study

-Address iron/ESA issues

Treatment of Complications

• Dyslipidemia

-Common, especially hypertriglyceridemia

-Limited data suggests lipid lowering may slow progression

Malnutrition

-Strong correlation between PCM and death

-Decreased intestinal absorption

-Renal diet

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Treatment of Complications

• Uremic bleeding

-Prolonged bleeding time secondary to impaired platelet function

-ddAVP, estrogen, dialysis

Pericarditis

Uremic Neuropathy

Thyroid Dysfunction

Predictors of Accelerated Progression

• Metabolic Syndrome

• Analgesics

• Obesity

• Smoking

• DM

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Predictors of Accelerated Progression

• Greater Proteinuria

• Higher BP

• Black race

• Lower HDL

• Lower Transferrin

Acute Renal Failure

• Abrupt decrease in Renal Function sufficient to result in retention of BUN and Creatinine

– Pre-renal vs intrinsic renal vs obstruction

– Most common is Acute Tubular Necrosis ie: ATN

– Frequency varies 2-5% of hospitalized

– 55% iatrogenic and sepsis

ARF in Hospitalized Patients

• Pre-renal azotemia is most common 30-60% of cases

• 1-10% post renal

• Intrinsic renal disease - ATN most common

• 40-60% of ATN occur in post-op or trauma

• AIN, Acute GN, CCE, Ureteral obstruction or intra-renal obstruction

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High-risk Setting for Acute Renal Failure

Clinical Setting Renal Failure %

General medical-surgical 3-5

Intensive care unit 5-25

Elective abdominal surgery 1-5

Open heart surgery 3-15

Abdominal aorta surgery 5-30

Severe burns 20-60

Aminoglycoside therapy 5-20

Radiocontrast exposure 0-30

Rhabdomyolysis 10-30

Sepsis 20-50

Causes of Acute Renal Failure

• Prerenal azotemia

• Renal azotemia

• Post renal azotemia (obstruction of collecting system)

Causes of Acute Renal Failure

• Prerenal azotemia – Absolute decrease in effective blood volume

Hemorrhage, skin losses (burns, sweating)

gastrointestinal losses (diarrhea, vomiting)

• renal losses (diuretics, glycosuria)

• fluid pooling (peritonitis, burns)

– Relative decrease in blood volume (ineffective arterial volume) • Congestive heart failure, sepsis, anaphylaxis, liver failure

– Arterial occlusion • Bilateral thromboembolism, thromboembolism of solitary kidney

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Prerenal Azotemia

• Is there hypotension?

• Is the patient on NSAIDS?

• ACEI?

• Renal Vascular disease?

• Check urine chemistries

Prerenal Azotemia

• FeNa <1%

• Hepatorenal syndrome

• Glomerulonephritis

• Transplant rejection

• Contrast

• Myoglobin

• Partial Obstruction

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Causes of Acute Renal Failure

• Renal azotemia – Vascular causes

• Vasculitis • malignant hypertension • microscopic polyarteritis

– Acute glomerulonephritis • Postinfectious glomerulonephritis • anti-basement membrane-antibody disease

– Acute interstitial nephritis • Drug-associated acute interstitial nephritis (methicillin

nephrotoxicity)

Causes of Acute Renal Failure

– Acute tubular necrosis • Ischemia

– Prerenal azotemia (if severe enough) – post surgical complication

• Sepsis syndrome • Nephrotoxicity

– Exogenous nephrotoxins » Antibiotics (aminoglycosides, cephalosporin, amphotericin B) » iodinated contrast agents » chemotherapeutic agents (cisplatin) » solvents (carbon tetrachloride, ethylene glycol)

– Endogenous nephrotoxins » Intratubular pigments (hemoglobinuria, myoglobinuria) » intratubular proteins (myeloma) » intratubular crystals (uric acid, oxalate) » tumor lysis syndrome

Causes of Acute Renal Failure • Postrenal azotemia (obstruction of collecting

system)

– Bladder outlet obstruction

– bilateral ureteral obstruction (unusual)

– ureteral obstruction in a solitary kidney

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Complications of ARF

• Volume overload

• Hyponatremia

• Hyperkalemia

• Acidosis

• Other Electrolyte Imbalances

• Anemia

Management of ARF

• Emergent intervention

• Supportive therapy

• Dialysis

• Dopamine

Indications for Initiation of Dialysis

• Pericarditis

• Progressive Uremic Encephalopathy

• Bleeding diathesis

• Fluid overload refractory to diuretics

• Hypertension poorly responsive to meds

• Persistent metabolic disturbances

• Persistent nausea and vomiting

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Prognosis of ARF

• 50-80% mortality of ARF associated with sepsis, hypotension and respiratory failure

• Oliguria 1 – 6 weeks

• Cost of dialysis and aggressive care is $128,000/life year saved

• Prevention is cornerstone in patient care

Community Acquired ARF

• Azotemia either acute or chronic

• 36% > 70

• Hypovolemia, NSAID, obstruction

• Dialysis if – Severe hyperkalemia

– Severe metabolic acidosis

– Marked fluid overload

– Signs/symptoms of uremia

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Tubulointersitial Disease

• Involves tubules and interstitium rather than glomeruli

– Obstructive Nephropathy

• Impaired outflow of urine

• Increased intratubular pressure, local ischemia, associated infection leading to TIN

• Diagnosis via ultrasound with Hydronephrosis +/- clinical suspicion

• Treatment is relieving obstruction

Reversible Causes of Kidney Failure

Nephrotoxic drugs -Aminoglycosides -NSAIDs -Iodinated contrast -? Gadolinium -Cimetidine,Tmp,Cefoxitin

Urinary Tract Obstruction

Reversible Causes of Renal Dysfunction

• Decreased renal perfusion

-Hypovolemia

-Hypotension

-Infection/sepsis

-Drugs

-Sodium avidity

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ATN – Acute Tubular Necrosis

• Initial decrease in renal blood flow then return to normal within 24-48 hours

• Tubular dysfunction persists

• Leakage of glomerular infiltrate

• Obstruction of flow by debris in lumen of tubules

• Decrease in glomerular capillary ultrafiltration

• Biochemical changes include mitrochondrial dysfunction, ATP depletion, oxygen free radicals

Radiocontrast

• Common

• Risk factors: CKD, DM, volume depletion, other nephrotoxins

• NaCl prevention: 1ml/kg/hr X 8 to 12 hrs prior

• Fenoldopam, selective D1 Dopamine receptor agonist

• Acetylcysteine

• Sodium Bicarbonate

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Angiotensin – Converting Enzyme Inhibitors

• Hemodynamic

• Loss of autoregulation of renal blood flow

• 30% increase creatinine acceptable when started

Aminoglycosides

• ATN in 10-20%

• Unrelated to therapeutic range

• Non oliguric

• 7-10 days of therapy

• ↓ urinary concentrating ability

• Potentiated by volume depletion, sepsis, liver ds, other nephrotoxins

• Once daily preferable

NSAIDs

• Inhibitors of PGE synthesis

• Volume depleted states ie: CHF, Cirrhosis, DM, CKD, Nephosis, sepsis, age, diuretics

• Hyperchloremic metabolic acidosis

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Rhabdomyolysis

• Trauma, ischemia, exercise, seizures, drugs, infections

• Metabolic derangements → hypo K, hypo PO4

• Cocaine, neuroleptic malignant syndrome and Hmg – CoA reductase inhibitors

• Muscle pain, dark urine, blood +, RBC – urine, ↑ CPK

• 1/3 develop ARF

• Rapid volume expansion and alkalinization

Microalbuminuria

• Normal < 20 mg/day

• 30-300 mg defines microalbuminuria

• > 300 mg/day Albuminuria

-Earliest finding of diabetic nephropathy

-Risk factor for cardiovascular disease (CVD)

Nephrotic Syndrome

• Proteinuria

• Edema

• Hypoalbuminuria

• Hyperlipidemia

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Causes of Nephrotic Syndrome

• Diabetes Mellitus ( DM )

• Membranous Nephropathy

• Focal Segmental Glomerulosclerosis ( FSGN )

• Minimal Change Disease

• Amyloidosis/Multiple Myeloma

• HIV Disease ( HIVAN )

Nephritic Syndrome

• Active intrinsic renal inflammation

– Hematuria

– Hypertension

– Acute Kidney Injury ( AKI )

– Edema

Renovascular Disease

• Large Vessel Renal Artery Disease ( RAS )

• Small Vessel Renal Artery Disease

• Thrombotic Microangiography

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Large Vessel Renal Artery Disease

• Etiology

– Atherosclerosis

– Fibromuscular Dysplasia ( young women )

– Unilateral-Hypertension without CKD

– Bilateral-Hypertension with CKD

Atherosclerotic Renal Artery Disease

• Risk Factors

– Smoking

– Diabetes Mellitus

– Hypertension

– Hyperlipidemia

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Case

• Principal Diagnosis

– Atherosclerosis of Renal Arteries 440.1

– Associated Codes

• Hypertensive renal disease 403.91

• Congestive heart failure 428.0

• Diabetes mellitus 250.40

• Coronary atherosclerosis 414.01