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Primary function of kidney
to filter blood or plasma to produce urine
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Secondary function of kidney
- maintain water and electrolyte balance
- maintain pH levels (both lungs and kidneys involved in acid-base balance)
- produce hormones
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Hormones produces in the kidney
- erythropoietin (RBC production)
- renin (BP regulation)
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Anatomy of the nephron
- afferent arterioles (carry blood to glomerulus)
- efferent arterioles (carry blood from glomerulus)
- glomerulus (filter unit of nephron)
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Anatomy of glomerulus
- glomerular capsule
- proximal convoluted tubule
- loop of Henle
- distal convoluted tubue
- juxtaglomerular apparatus
- collecting duct
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Formation of urine
- three part process takes place in different parts of nephron
- 1) glomerular filtration
- 2) tubular reabsorption
- 3) tubular secretion
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Glomerular filtration
- osmotic concentration similar to that of plasma
- blood in glomerulus has two components: filterable and nonfilterable
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Tubular reabsorption
- occurs as molecules and ions are both passively and actively reabsorbed from the nephron into the blood
- osmolarity of blood is maintained by presences of both plasma proteins and salts
- urine concentration increases/decreases as it descends/ascends the nephron cortex and medullary due to substance not reasborbed
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Non-filterable components of blood in glomerulus
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Tubular secretion
second way by which substances are removed from blood and added to tubular fluid
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Other substances that regulate salt and water reabsorption
- aldosterone (mineralcorticosteroid)
- antidiuretic hormone (ADH)
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Indicators of disease
- changes in urination
- chills and fever
- dysuria
- edema (caused by plasma protein loss)
- fatigue
- hematuria
- hypertension
- loss of appetite
- proteinuria (foamy urine due to protein levels)
- pyuria
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Diagnostic tests or procedures
- urinalysis (physical or gross appearance of urine)
- dipstick
- microscopy
- cystoscopy
- intravenous pyelogram (IVP)
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Red urine
- indicative of blood, hemoglobin or beets
- Further proof that no one should ever eat beets
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Beer-brown urine
bilirubin
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Black urine
- melanin
- indicates that cancer has spread to liver
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Orange, blue or green urine
presence of food, dye or food metabolites
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Turbidity of urine
- well-mixed sample will be either clear or turbid
- normal urine is clear
- centrifuge to determine if cause is cells or crystals (cloud settles to bottom) or bacterial (remains cloudy)
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Strong odor
- normal urine smells like pee
- normal asparagus also smells like pee
- ketones smell fruity or like nail polish remover
- nail polish remover does not smell like pee. Obvs Pete is sniffing something.
- fecal smells indicate that urine is putrid
- ammonia smells indicate alkaline urine (pH ~8-9)
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Parameters measured in dipstick tests
- pH
- specific gravity
- albuminuria
- glucose
- ketones
- nitrites
- leukocyte esterase
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Causes of high urinary pH (alkali urine)
- diet - vegetarian, low carb, lots of citrus fruit
- systemic alkalosis
- renal tubular acidosis
- fanconi syndrome
- UTI
- certain drugs (amphotercin B, carbonic anhydrase inhibitors, NaHCO3, salicylate OD)
- stale ammoniacal sample
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Causes of low urinary pH (acidic urine)
- diet - high protein or lots of fruits (like cranberries)
- systemic acidosis
- diabetes mellitus
- starvation
- diarrhea
- malasorption
- phenylketonuria
- alaptonuria or alacaptonuria
- renal tuberculosis
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Causes of decreased gravity
- You're on the moon!
- excessive hydration
- nephrogenic diabetes insipidus
- acute glomerulonephritis
- pyelonephritis
- acute tubular necrosis
- alkaline urine
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Causes of fixed specific gravity
- chronic renal failure
- chronic glomerulonephritis
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Causes of increased specific gravity
- You're on Mars!
- dehydration
- syndrome of inappropriate antidiuretic hormone hypersecretion
- adrenal insufficiency
- pre-renal failure
- hyponatremia with edema
- liver failure
- nephrotic syndrome
- glycosuria
- proteinuria
- IV contrast dye
- urine contamination
- low molecular weight dextran solution
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Causes of albuminuria
chronic kidney disease
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Causes of glucose in urine
diabetes mellitus
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Causes of hematuria
- glomerulonephritis
- kidney stones
- tuberculosis
- cystitis
- tumors
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Causes of microscopic particles in urine
- pyuria
- casts: fatty, granular, hyaline, RBC, renal tubular epithelial, waxy, WBC
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Abnormalities identified by cystoscopy
- blood in urine
- inflammation
- kidney stones
- polyps
- tumors of urinary bladder or ureter
- urethral strictures or narrowings
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Abnormalities identified by intavenous pyelogram (IVP)
- urinary bladder and kidney infections
- blood in urine
- flank pain possibly due to kidney stones
- tumors
- urinary tract damage after an abdominal injury
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Glomerulonephritis
- inflammatory disease of glomeruli affecting the filtering waste and fluids from the blood
- usually caused by antigen-antibody (Ag-Ab) reaction following a hemolytic streptococcal infection
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Process of glomerulonephritis
- Ag-Ab complexes form in blood becoming trapped in glomeruli and triggering an inflammatory response
- neutrophils respond to inflamed glomeruli
- glomerular blood flow is reduced and impede the filtration rate resulting in decreased urine formation
- glomeruli degenerate and become extremely permeable
- albumin and RBCs appear in urine
- kidney failure may occur, leading to accumulation of dangerous levels of fluid and waste in body
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Causes of glomerulonephritis
- post-steptococcal glomerulonephritis
- bacterial endocarditis
- viral infections
- immune diseases (systemic lupus erythematosus or nephritis, Goodpasture's syndrome, IgA nephropathy, vaculitis [polyarteritis, Wegener's granulomatosis]
- HPB
- diabetes kidney disease
- focal segmental glomerulosclerosis
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Signs and symptoms of glomerulonephritis
- chills and fever
- loss of appetite
- fatigue or weakness from anemia or kidney failure
- edema
- less frequent urination
- hematuria
- proteinuria
- hypertension
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Treament of acute glomerulonephritis
- bed rest
- dietary restrictions
- medications (calcium channel blockers, beta-adrenergic receptor antagonists)
- diuretics
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