Medical Technology Assessment Comprehensive Review: Urinalysis and Body Fluids

Comprehensive flashcard set for urinalysis and body fluid analysis review, covering anatomy, physiology, chemical/physical/microscopic examination, and specialized fluids like CSF, synovial, serous, semen, and amniotic fluid.

Abdominal Aorta

Carries oxygenated blood from the heart to various parts of the lower body.

Renal Artery

Branches off the abdominal aorta, delivering oxygenated blood to the kidneys for filtration.

Kidney

Filters waste products, excess salts, and water from the blood to form urine, and returns filtered blood.

Renal Vein

Carries filtered (deoxygenated) blood from the kidneys back towards the heart.

Inferior Vena Cava

Receives filtered blood from the renal veins and other lower body veins and returns it to the heart.

Ureter

Transports urine from the kidneys to the urinary bladder.

Urinary Bladder

Stores urine until a sufficient volume accumulates and the urge to urinate is felt.

Urethra

Carries urine from the urinary bladder out of the body during urination.

Retroperitoneum

The posterior abdominal wall where bean-shaped kidneys are located.

Renal Hilus

Indentation through which the renal artery enters and the renal vein and ureter exit.

Cortex

Outer layer of the kidney; exclusive site of the plasma filtration process.

Medulla

Inner layer of the kidney; consist of renal tissue shaped into pyramids.

Nephron

Basic structural and functional unit of the kidney, with 1 to 1.5 million per kidney.

Proximal tubule

Responsible for the reabsorbing essential nutrients and water from the filtered fluid.

Loop of Henle

Helps control the concentration of urine by reabsorbing water and electrolytes.

Distal tubule

Responsible for fine-tuning the composition of urine by adjusting electrolyte and water balance.

Collecting ducts

Collects urine from multiple nephrons and carries it to the renal pelvis.

Cortical Nephrons

Majority of nephrons (80-85%), responsible primarily for removal of waste products and reabsorption of nutrients.

Juxtamedullary Nephrons

Nephrons with longer loops of Henle that extend into the medulla; primary function is concentration of urine.

Ascending Loop of Henle

Part of the nephron that is highly impermeable to water.

Afferent Arteriole

Controls blood flow into the glomerulus.

Efferent Arteriole

Carries blood away from the glomerulus.

Peritubular Capillaries

Reabsorbs useful substances and secretes waste around renal tubules.

Vasa Recta

Maintains the osmotic gradient for urine concentration.

Renal Blood Flow

The volume of blood delivered to the kidneys, approximately $1200\,mL/min$.

Renal Plasma Flow

The volume of plasma delivered to the kidneys, approximately $600-700\,mL/min$.

Cardiac Output to Kidneys

Approximately $25\%$ of blood from the heart enters the kidney.

Glomerulus

A coil of approximately eight capillary lobes that acts as a nonselective filter for substances with molecular weights $< 70,000$.

Glomerular Filtration Barrier

Consists of the capillary wall membrane, basement membrane, and visceral epithelium of Bowman capsule.

Fenestrated endothelium

Pores in the capillary wall membrane that increase permeability but block large molecules and blood cells.

Podocytes

Cells in the visceral epithelium with intertwining foot processes forming filtration slits.

Shield of Negativity

A property of the glomerular filtration barrier that repels negatively charged molecules like albumin.

Juxtaglomerular Apparatus

Autoregulates glomerular blood pressure by adjusting afferent and efferent arteriole size.

Renin

An enzyme that initiates the RAAS by cleaving angiotensinogen into angiotensin I.

Angiotensin I

A relatively inactive intermediate in the RAAS converted to angiotensin II by ACE.

Angiotensin II

Primary active hormone of RAAS; causes vasodilation of afferent arterioles and release of aldosterone and ADH.

Aldosterone

Regulates sodium and potassium balance and increases blood volume and pressure.

Anti-Diuretic Hormone (ADH)

Also known as Arginine Vasopressin (AVP); primary function is to conserve body water.

Tubular Reabsorption

Process where renal tubules recover essential substances (salts, water, glucose, urea) and return them to the blood.

Threshold Substances

Substances completely reabsorbed by renal tubules when plasma concentration is within normal limits.

Renal threshold for Glucose

The plasma concentration level of $160-180\,mg/dL$.

Diabetes Insipidus (DI)

Condition caused by ADH deficiency, leading to kidneys being unable to reabsorb water.

SIADH

Syndrome of Inappropriate ADH Secretion, characterized by ADH excess.

Active Transport

Movement of substances back to the bloodstream using electrochemical energy and carrier proteins.

Passive Transport

Movement of molecules across a membrane by diffusion due to a physical gradient.

Countercurrent Mechanism

Process in the Loop of Henle that creates and maintains the medullary osmotic gradient.

Tubular Secretion

Process involving regulation of acid-base balance and elimination of waste products not filtered by the glomerulus.

Bicarbonate Reabsorption

Renal process maintaining blood buffering capacity by preventing HCO3- excretion.

Ammonia Production

Breakdown of glutamine in the PCT to form NH4+ which is excreted in urine.

Renal Tubular Acidosis

Inability to produce acid urine due to defects in H+ secretion, ammonia production, or bicarbonate reabsorption.

Ultrafiltrate

Urine composition identical to blood plasma but normally free of protein ($< 10\,mg/dL$).

Average Daily Urine Output

Approximately $1,200\,mL$ derived from $170,000\,mL$ of filtered plasma.

Urine Composition - Water

Comprises $95\%$ of normal urine.

Urea

The major organic substance in urine, a product of protein and amino acid metabolism.

Chloride

The major inorganic component of urine.

Creatinine

Product of metabolism of creatine by muscles; used to identify unknown fluid as urine.

Uric Acid

Product of the breakdown of nucleic acid in food and cells.

Oliguria

Decreased urine volume ($< 400\,mL/day$ in adults) often seen in dehydration.

Polyuria

Increased urine volume ($> 2.5\,L/day$ in adults) associated with diabetes.

Anuria

Cessation of urine flow ($< 100\,mL/24hrs$).

Nocturia

Increase in the nocturnal excretion of urine ($> 500\,mL$ at night).

Diabetes Mellitus Polyuria

Caused by insulin defect; kidneys excrete excess glucose requiring increased water excretion.

Diabetes Insipidus Polyuria

Caused by decreased ADH; urine is truly dilute with low specific gravity.

Urine Container Capacity

Range of $50\,mL - 100\,mL$ for routine UA and $3000\,mL$ for timed specimens.

Random Specimen

Collected anytime; useful for routine screening and obvious abnormalities.

First Morning Specimen

Concentrated specimen ideal for pregnancy tests (hCG) and orthostatic proteinuria.

24-Hour Specimen

Used for accurate quantitative results and assessing GFR or diurnal variations.

Catheterized Specimen

Sterile specimen obtained directly from the bladder; best for urine culture.

Midstream Clean-Catch

Non-invasive specimen for culture; represents bladder, ureters, and kidneys.

Suprapubic Aspiration

Invasive specimen for culture or cytology completely free of extraneous contamination.

Urine Testing Timeframe

Should be delivered and tested within $2\,hours$ of collection.

Darkened Urine Color

Caused by oxidation or reduction of metabolites in unpreserved urine.

Ammoniacal Odor

Caused by bacterial breakdown of urea in unpreserved urine.

Increased pH in Urine

Caused by breakdown of urea to ammonia or loss of $CO_2$ in unpreserved specimens.

Decreased Glucose in Urine

Caused by glycolysis and bacterial use in unpreserved specimens.

Decreased Bilirubin in Urine

Caused by exposure to light and photo oxidation to biliverdin.

Urochrome

The major lipid-soluble pigment providing yellow color to urine.

Uroerythrin

Pink pigment that deposits in amorphous urates, known as brick dust.

Urobilin

Pigment that imparts an orange-brown color to urine that is not fresh.

Colorless Urine

Associated with recent fluid consumption or random specimens.

Pale Yellow Urine

Associated with polyuria, diabetes insipidus, or diabetes mellitus.

Dark Yellow Urine

Associated with concentrated specimens, dehydration, fever, or B complex vitamins.

Yellow Foam

Indicates the presence of bilirubin when urine is shaken.

Orange-Yellow Urine

Associated with the drug Phenazopyridine (Pyridium) used for UTIs.

Blue-Green Urine

Associated with Amitriptyline, Methocarbamol, or Pseudomonas infections.

Port Wine Urine

Associated with the presence of porphyrins.

Red-Brown Urine

Caused by RBCs oxidized to methemoglobin in acidic urine.

Black Urine

Associated with Malignant melanoma, melanin, or homogentisic acid.

Nubecula

A faint cloud in normal urine after standing due to WBCs, epithelial cells, and mucus.

Turbidity Soluble with Heat

Indicates the presence of amorphous urates or uric acid crystals.

Turbidity Soluble in Dilute Acetic Acid

Indicates the presence of RBCs, amorphous phosphates, or carbonates.

White Foam (Large Amount)

Indicates the presence of protein in urine.

Aromatic Odor

Normal urine odor due to volatile acids from food.

Mousy Odor

Associated with Phenylketonuria (PKU).

Maple Syrup Odor

Associated with Maple Syrup Urine Disease (MSUD).

Fruity Odor

Associated with Diabetes ketoacidosis.

Rotting Fish Odor

Associated with Trimethylaminuria.

Urinometry

Measurement of specific gravity using a hydrometer weighted float.

Specific Gravity Temperature Correction

Add or subtract $0.001$ for every $3^{\circ}C$ above or below $20^{\circ}C$.

Refractometry

Measures refractive index to determine specific gravity; compensated between $15^{\circ}C$ and $38^{\circ}C$.