Clinical Microscopy- Boards

Urine

Liquid tx biopsy of urinary tract

Urine

Ultrafiltrate of plasma with waste products

90% water

10% solutes

Composition of plasma

95% water

5% solutes

Composition of urine

Cl

Major inorganic component of urine

Na

K

SO4

PO3

Other inorganic components of urine

Urea

Major organic component of urine

Creatinine

Uric acid

Hippuric acid

Other organic components of urine

600-2000 mL

Normal output of urine

Polyuria

Inc. urine output

Oliguria

Dec. urine output

Anuria

Cessation of urine flow

Dysuria

Painful urination

Nocturia

Inc. urine output at night

>500mL with sg <1.018

2:1-3:1

Normal day:night urine

Normal urine

Clear

Straw (pale yellow) to amber

Urochrome

Yellow pigment

Inc. in fever, thyrotoxicosis and starvation

Uroerythrin

Pink pigment

Refrigerate

Ppt. amorphous urates

Urobilin

Orange-brown pigment

Oxidation product

No longer fresh

Urobilinogen

Colorless

Converted by bacteria

Kidneys

Ureters

Urinary bladder

Urethra

Components of renal/ excretory system

Kidneys

Main organ of excretory system

Produces EPO and renin

Erythropoietin

Stimulated by tissue hypoxia

Renin

Maintains BP

Aldosterone production

Urinary bladder

Temporary storage of urine

Nephron

Functional unit of kidney

1M-1.5M

Renal blood flow

Glomerular filtration

Tubular reabsorption

Tubular secretion

Mechanism of urine formation

20-25%

Cardiac output received by kidney

1200 mL/min

Renal blood flow

600-700 mL/min

Renal plasma flow

Test renal function if:

DM

Hypertension

Diabetes mellitus

Insulin

Inc. sg due to glucose

Diabetes insipidus

ADH (vasopressin)

Dec. sg

Afferent arterioles

Formed from renal artery

Blood towards nephrons

Glomerulus

Filtering apparatus

Sg constant at 1.010

pH 7.4

Osm similar to plasma

Criteria of filtration by glomerulus

Size

Charge

PCT

65-80% reabsorptiom process

Countercurrent mechanism

DLH permeable to water, not salt

ALH permeable to salt, not water

ADH acts on

DCT and CD

Water reabsorption

Renal tubules

Conc. and dilute urine

PCT LH DCT CD

PCT

Glucose

Amino acids

Electrolytes

DLH

Water

ALH

Na

Cl

DCT and CD

Water

Require ADH

Glomerular filtration

Clearance tests

Urea

Inulin

Creatinine

Urea clearance

Affected by diet (protein metab)

~40% is reabsorbed by the tubules

Creatinine clearance

Most common

only ~1% is reabsorbed

Error: improperly collected urine sx

Inulin clearance

Gold standard

Invasive (exogenous substance)

Polymer of fructose

Calculated glomerular filtration estimates

Cockcroft and Gault's formula

Modification of Diet in Renal Disease (MDRD)

Other tests for GFR

Cystatin C

β2 microglobulin

125I-iothalamate

mL/min

Unit of GFR

Crea clearance needs

24h urine

Serum/plasma crea