NPN study guide

Normal values for creatinine

Plasma: F- 0.5-1

M-0.7-1.3

24hrs urine: F-0.6-1.8

M-0.8-2

Normal values for urea

Plasma: 8-25mg/dl

Urine: 12-20g/24hrs

Normal values for uric acid

Plasma: M: 3.2-8.6mg/dl

F: 2.2-7.1 mg/dL

Urine: 250-750g/24hrs

How is creatinine created

• creatine is synthesized in the kidney, liver, and pancreas

• transported to muscle and brain an converted to Phosphocreatine by CK

• during non enzymic spontaneous reaction makes creatine→ creatinine

Creatinine is the best measurment for

CKD

increased levels of CK are associated with

decreased glomerular function

Jaffe reaction

is a reaction with alkaline picrate creating a colored solution

How does the jaffe reaction work

The intensity of the color correlates with the creatinine concentration in the sample.

What does the jaffe reaction lack

specificity

What can interfere with the jaffe reaction

• ascorbic acid

• glucose

• ketone

• protein

• pyruvate

Creatinase is better for what population

pediatric

Cause of error in creatinine clearance

• some creat is secreted by tubules

• chromogens in plasma react with analysis

• bacterial breakdown at room temp

• diet heavy in meat can alter results

• Not reliable in muscle-wasting diseases

CRCL formula

(UxV)/P

What does the creatinine clearance test tell the patient

how well their kidneys are working

Urea is created from

catabolism on proteins and amino acids

What test measures urea in the blood

BUN

high levels of BUN (uremia)are associated with

renal complications

mmol/L to mg/dL urea conversion factor is

0.375 (BUN is multiplied, Urea is divided)

Pre-renal Azotemia causes

• blood loss

• MI or CHF

• Shock/hemmorage

• Liver failure

• High protein intake

• Severe dehydration

Azotemia

Fluid wont go through the kidneys fast enough

Azotemia examples

• Glomerular nephritis

• tubular necrosis

• acute and chronic renal failure

Post-renal Azotemia examples

• kidney/bladder stones

• genitourinary tumors

• prostate cancer

• UTI

Uric acid is the product of

Purine metabolism

Hyperuricemia is at what number

>7g/dl in plasma

What causes hyperuricemia

• defective enzymes

• increased cell turnover

• insufficient renal excretion of UA

Primary gout

inherited over production of purine or underexcretion of uric acid

secondary gout

The result of renal retention of uric acid that can occur with acute and chronic renal disease