Kidney Disease:

How much work up and when

to refer?

Les Spry, MD FACP FASN FNKF

Lincoln Nephrology &

Hypertension

Dialysis Center of Lincoln

Definition of Chronic Kidney

Disease (CKD)• Kidney damage for > 3 months, with or

without decreased GFR

• Kidney damage defined as abnormal

pathology or urinary findings of blood,

pyuria &/or proteinuria, or abnormal

imaging studies for more than 3 months

• GFR < 60 ml/min/ 1.73 meters squared for

> 3 months with or without kidney damage

Stages of CKD

Stage Description GFR(ml/min/ 1.73 m2)

Action

0 At increased risk > 90 Screen for CKD – Rx

risk factors

1 Kidney damage with

normal or increased GFR> 90 Diagnose, slow progression

and treat risk factors

2 Kidney damage with mild

decrease in GFR60 - 89 Above plus estimate

progression

3 Moderate decrease in

GFR30 - 59 Above plus educate &

treat complications

4 Severe decrease in GFR 15-29 Prepare for transplant

and replacement Rx

5 Kidney failure < 15 Transplant and renal

replacement RX

Chronic Kidney Disease

• Hence, CKD relies on the demonstration

that kidney disease has been present for

more than 3 months.

• It results from an absolute loss of

nephrons and glomeruli that decrease the

glomerular filtration rate

• We often look back at old records to

determine if kidney disease could be

defined in past records.

Risk Factors for CKD

• Diabetes

• Hypertension

• Autoimmune disease

• Systemic infection

• UTI’s

• Obstructive uropathy

• Family history

• Acute kidney injury

• Nephrectomy

• Drug exposure (ie NSAID’s and analgesics)

• Low birth weight

• Ethnic minorities (ie Black, American Indian, Hispanic, Asian or Pacific Islander)

• Low socioeconomic and education

Acute Kidney Injury

• Definition: The sudden and unexpected

decrease in glomerular filtration rate.

Oliguric = < 400 cc per day

Nonoliguric = > 400 cc per day

Anuria = < 50 cc per day

New Criteria for definition for

Acute Kidney Injury• RIFLE = Risk, Injury, Failure, Loss and

ESRD

• AKIN = Acute Kidney Injury Network

Classification

Comparison of AKI staging by

RIFLE versus AKIN RIFLE

Stage

RIFLE

Serum

Creatinine

Increase

RIFLE & AKIN

Urine output

criteria

AKIN Serum

Creatinine

Increase

AKIN

Stage

Risk >150 to

200%

< 0.5 ml/kg per

hour for > 6

hours

> 0.3 mg/dl or

> 150 to

200%1

Injury > 200 to

300%

< 0.5 ml/kg per

hour for 12

hours

> 200 to

300% 2

Failure > 300%

< 0.3 ml/kg per

hour for > 24

hours or anuria

for > 12 hours

> 300 % or

acute renal

replacement

therapy

3

Increasing Mortality with each

Stage of AKI in ICU

AKIN or RIFLE

Stage

Increase in

mortality

Stage 1 or R 29%

Stage 2 or I 32%

Stage 3 or F 42%

Oliguria

• If the maximum urinary concentrating

ability is 1200 mOsm/ kg

• If the ordinary requirement for osmolar

excretion is 400 to 500 mOsm per day

• Then the minimum amount of urine that

should be produced per day in a normal

individual is about 400 cc per day (0.25 cc

per kg per hour).

Anuria

Differential Diagnosis:

1. Obstruction

2. Acute vascular event

a. Renal vein or arterial event

b. Acute cortical necrosis

DX: 1. Bladder catheterization

2. Renal and bladder ultrasound

3. Renal scan?

Functions of the Kidney

1. Excretory

(Toxins, Drugs and Endogenous Wastes)

2. Re-absorptive

(Salt, Water, and Nutrient Reclamation)

3. Metabolic

(Acid-Base, Glucose, Drug Detoxification)

(Hormone Degradation and Excretion)

Acute vs. Chronic Kidney

Disease

Acute Chronic

Rising Creatinine High

Rising BUN High

Low Hemoglobin Lower

Normal Calcium Low

Normal Phosphate High

High Potassium Normal or High

Progressive Acidosis Mixed

Uncommon Hypertension Usual

Many casts Urine sediment Few casts

Oliguric Urine Output Maintained

Normal size Kidney U/S Small and Scar

Estimates of GFR

• Creatinine

• BUN

• Creatinine Clearance

• Urea Clearance

• Cockroft-Gault Creatinine Clearance

• MDRD calculated GFR

• MDRD or CKD-EPI equation (Creatinine to

two decimal points)

Acute Kidney Injury

• Pre-renal azotemia

1. Volume Depletion

2. Congestive Heart Failure

3. Severe liver disease

4. Early acute tubular necrosis

5. Severe nephrosis

6. Early sepsis

Frequently has a benign urinalysis

Acute Kidney Injury

• Post Renal Azotemia

1. Palpable bladder

2. Hydronephrosis on ultrasound

3. Enlarged prostate

4. Renal calculi

5. Abnormal pelvic examination

6. Frequently benign urinalysis

Acute Kidney Injury

Urinalysis

Eosinophilia RBC casts, proteinuria or both Granular casts and pigmented casts

Interstitial Nephritis Glomerulonephritis or vasculitis Acute Tubular necrosis

• Order spot urine for Sodium, Potassium,

Creatinine & Osmolality

• Order spot urine for eosinophils by Hansel’s

stain

Algorithm for Red Urine

Acute Kidney Injury

Post Traumatic Acute Renal Failure was

reduced in incidence from

1 : 200 in the Korean War

to

1 : 600 in the Vietnam War

by the simple policy change of administering

IV fluid in the field and volume repleting

causalities as soon as possible.

Specific therapy for Acute Kidney

Injury

• Acetaminophen

• Heavy metal intoxication

• Hypercalcemia

• Tumor lysis syndrome

• Myeloma kidney

• Ethylene glycol (fomepazole)

• Myoglobinuria

• Hemoglobinuria

Myoglobinuria therapy

• Aggressive hydration

• Crush formula = ½ normal saline plus 12.5

grams of 25% mannitol plus 50 mEq of

sodium bicarbonate per liter at 200 cc per

hour

• Dialysis therapy for those who fail

hydration therapy

Risk Factors for Contrast

• Age > 65

• Pre-existing kidney disease

• Dehydration

• Diabetes Mellitus

• Proteinuria

• Hyperuricemia/ Gout

• Congestive Heart Failure

• Large volume contrast

• Multiple Myeloma

Contrast Prophylaxis

1. Mucomyst 600 mg BID for four doses

2. ½ normal saline at 125 cc/hour for 12 hours

prior to procedure and continued for 24 hour

post procedure

3. ? Normal saline at 1cc/kg/hour

4. D5/water plus 150 mEq sodium bicarbonate

per liter at 300 cc per hour for one hour prior to

procedure and then 1 cc per Kg per hour to

complete the liter after the procedure.

Acute Kidney Injury Therapy

• Start nutrition early

• Renal Failure formula = D5/water plus 100-150 mEq sodium bicarbonate per liter plus 10 units of insulin per liter at 40 – 60 cc per hour

• Evaluate for dialysis therapy

• Treat hyperkalemia and acidosis

• Telemetry

• Review all drugs and doses

Therapy of Hyperkalemia

• Calcium Chloride 1 gram IV

• Sodium bicarbonate

• Albuterol nebulizer

• One ampule of D/50 with 12-15 units

regular insulin IV (give the insulin first)

• Kayexalate 15 gram vials mixed in sorbitol

solution

• Dialysis

High Dose Loop Diuretic Therapy

• Assure volume repletion

• Assure oxygenation

• Obtain urinary studies

• Use adequate doses (5mg/kg furosemide)

• Some studies have suggested an

improved outcome associated with non-

oliguric status achieved with high dose

diuretic

Acute Kidney Injury

• There is no value in the use of low dose Dopamine for the treatment of ARF unless decreased EF is also present. Risk = arrhythmia

Acute Kidney Injury

• First assess volume. If hypervolemic, then

patient will need access to dialysis therapy

• If pericarditis, patient will need access to

dialysis therapy.

• In all other cases, start alternative renal

failure formula: Plain ½ normal saline with

50 mEq of Sodium Bicarbonate per liter

and run at rate so as to avoid volume

overload. (Acidosis is less severe)

Acute Kidney Injury

• Monitor with telemetry to evaluate peaked

T-waves and for arrhythmia.

• Place foley catheter after urinalysis has

been done to assess urinary findings

• Order a kidney ultrasound to look for

reversible causes of kidney disease

• High dose Lasix to be considered if

adequate volume and oxygenation.

Indications for Dialysis

1. Hypervolemia

2. Hyperkalemia

3. Acidosis

4. Pericarditis

5. “Uremia”

6. “Catabolic State”

Thank You

•Questions?