Kidney Function

Question 1

Acute Glomerulonephritis

Answer 1

Hematuria, proteinuria, and oliguria. Also seen are RBC casts, dysmorphic RBCs, hyaline and granular casts and WBCs. BUN may be elevated. May demonstrate a positive ASO titer. Cloudy, red, positive protein and blood.

Question 2

Discuss the pathogenesis of this condition and the projected outlook for the patient.

Answer 2

Damage to the glomerular membrane. Symptoms include fever; edema, fatigue, hypertension, oliguria, and hematuria. Usually occur in children and young adults following group A Streptococcus infections. . The Streptococcus organisms form immune complexes with their corresponding circulating antibodies and causes glomerulonephritis.

Question 3

Discuss the anatomy and physiology of the glomerulus.

Answer 3

The glomerulus consists of a coil of approximately eight capillary lobes known as the capillary tuft that is housed within the Bowman’s capsule.

Question 4

Rapid Progressive glomerulonephritis(RPGN) crescentic glomerulonephritis

Pathogenesis
Glomerular Changes
Urinalysis
Chemistry Tests

Answer 4

Pathogenesis: antibody mediated often antibodies to the glomerular basement membrane

Glomerular changes: the cells of the Bowman’s space form crescents; leukocytic infiltration; fibrin deposits, GBM disruption

Urinalysis: gross hematuria, proteinuria, and RBC casts.

Chemistry Tests: increased BUN, Creatinine, decrease creatinine clearance

Question 5

Membaranous glomerulonephritis(MGM)

Pathogenesis
Glomerular Changes
Urinalysis
Chemistry Tests

Answer 5

Pathogenesis: Antibody mediated

Glomerular changes: basement membrane thickens as a result of antibodies and complement deposits, loss of foot cell processes

Urinalysis: RBC’s, proteinuria

Chemistry Tests: Antinuclear antibodies, hepatitis B antigens, FTA-ABS

Question 6

Membranoproliferative glomerulonephritis(MPGN)

Pathogenesis
Glomerular Changes
Urinalysis
Chemistry Tests

Answer 6

Pathogenesis: Immune complex or complement activation

Glomerular changes: cellular proliferation of the mesangium, leukocytic infiltration, IgG and complement deposits

Urinalysis: RBC’s, proteinuria

Chemistry Tests: increased serum compliment levels

Question 7

Chronic Glomerulonephritis

Pathogenesis
Glomerular Changes
Urinalysis
Chemistry Tests

Answer 7

Pathogenesis: Variable

Glomerular changes: hyalinized glomeruli

Urinalysis: RBC’s, hematuria, proteinuria, glucosuria and granular, waxy, and broad casts

Chemistry Tests: decreased glomerular filtration rate and an increased BUN and creatinine levels. Electrolyte imbalance.

Question 8

IgA nephropathy

Pathogenesis
Glomerular Changes
Urinalysis
Chemistry Tests

Answer 8

Pathogenesis: IgA mediated; compliment activation

Glomerular changes: Deposits of IGA in mesangium, variable cellular proliferation

Urinalysis: Early stages hematuria. Late stages RBC’s, hematuria, proteinuria, glucosuria and granular, waxy, and broad casts

Chemistry Tests: increased serum IgA

Question 9

Focal segmented glomerulosclerosis(FSGS)

Pathogenesis
Glomerular Changes
Urinalysis
Chemistry Tests

Answer 9

Pathogenesis: Unknown possibly a circulating systemic factor; can reoccur after kidney transplant

Glomerular changes: sclerotic glomeruli with hyaline and lipid deposits(focal and segmental) diffuse loss of foot processes; focal IgM and C3 deposits

Urinalysis: RBC’s, proteinuria

Chemistry Tests: drug testing and genetic testing.

Question 10

Pyelonephritis

Macroscopically
Microscopically

Answer 10

Macroscopically-cloudy urine, protein, blood, nitrites, leukocyte esterase
Microscopically-WBCs, renal epithelial cells, WBC casts, moderate bacteria

Question 11

Proximal tubule

Mode of Reabsorption and Substance

Answer 11

Passive - H2O, Cl-, K+, urea

Active - Na+, HCO3-, glucose, proteins, phosphate, sulfate, Mg+, Ca2+, uric and amino acids

Question 12

Loop of Henle

Mode of Reabsorption and Substance

Answer 12

Thin descending - Passive - H2O, urea

Loop of Henle - Passive - Na+, Cl-, urea

Thick ascending(medullary and cortical) - Passive - urea
                                                                      Active - Na+, Cl-

Question 13

Distal Tubule (convoluted portion)

Mode of Reabsorption and Substance

Answer 13

Passive - H2O

Question 14

Collecting Tubules

Mode of Reabsorption and Substance

Answer 14

Cortical Passive - H2O, Cl-
Active - Na+

Medullary Passive - H2O, urea

Question 15

Discuss where the ultrafiltrate components are secreted in the nephron.

Proximal Tubule
Loop of Henle
Distal Tubule
Collecting Tubules

Answer 15

Proximal tubule - H+, NH3, weak acids and bases

Loop of Henle - Urea

Distal Tubule (convoluted portion) - H+, NH3, K+, uric acid

Collecting Tubules - H+, NH3, K+

Question 16

Acute Pyelonephritis

Physical and Chemical Examination
Microscopic Examination

Answer 16

Physical and Chemical Examination
Protein: small(<1.0 g/day)
Blood: positive(usually small)
Leukocyte esterase: positive
Nitrite: positive
Specific Gravity: normal to low

Microscopic exam
WBCs clumps, Bacteria (GNR), RBC’s, Renal epithelial cells, WBC, granular, renal cellular, waxy casts

Question 17

Chronic Pyelonephritis

Physical and Chemical Examination
Microscopic Examination

Answer 17

Physical and Chemical Examination
Protein: moderate(2.5 g/day)
Leukocyte esterase: positive
Specific Gravity: low

Microscopic exam
WBCs, WBC, granular, renal cellular, waxy, broad casts

Question 18

Acute interstitial nephritis

Physical and Chemical Examination
Microscopic Examination

Answer 18

Physical and Chemical Examination
Protein: mild(~1 g/day)
Blood: positive
Leukocyte esterase: positive

Microscopic exam
WBCs Increased eosinophils , RBC’s, Renal epithelial cells, WBC, granular, renal cellular, waxy, broad casts

Question 19

Cystitis

Physical and Chemical Examination
Microscopic exam

Answer 19

Physical and Chemical Examination	
Protein: small(<0.5 g/day)
Blood: positive(usually small)
Leukocyte esterase: positive
Nitrite: positive

Microscopic exam
WBCs, Bacteria, RBC’s, Transitional epithelial cells

Question 20

Nephrotic syndrome

Macroscopic and Microscopic

Answer 20

Macroscopically: cloudy/foamy urine, large amount of protein, small amount of blood

Microscopically: renal cells and hematuria, granular, waxy, fatty casts, oval fat bodies, urinary fat droplets, renal tubular epithelial cells, epithelial, renal, fatty, and waxy casts,

Question 21

Discuss the disease process of nephrotic syndrome

Answer 21

Clinical features that happen all at once and can happen as a result of glomerulonephritis, circulatory shock , or decreased blood flow to the kidney. Massive proteinuria >3.5, low serum albumin and high serum lipids

Question 22

BUN

Definition and reference range

Answer 22

BUN or Blood Urea Nitrogen: Is the amount of nitrogen found in the blood from breakdown of Urea which is filtered by the glomerulus. Most of it is excreted in the urine however 40% is reabsorbed in the renal tubules.

BUN: 6-20 mg/dL

Question 23

Creatinine

Definition and reference range

Answer 23

Creatinine is the breakdown product of creatine phosphate in muscle and is released into the circulation at a constant rate and is directly proportional to a person’s muscle mass. Creatinine is filtered by the glomerulus and excreted in the urine.

Females-0.5-0.8 mg/dL
Males-0.6-1.1 mg/dL

Question 24

BUN creatinine ratio

Definition and reference range

Answer 24

The BUN creatinine ratio compares the two results and used to determine either acute kidney damage or dehydration.

20:1

Question 25

Calculate the creatinine clearance, list the reference intervals for both males and females. Emphasize why the creatinine clearance is a good indicator of kidney function.

Answer 25

``` Clearance = U x V / P U = urine creatinine conc. (mg/dL) V = urine volume (mL/min) P = Plasma creatinine conc. (mg/dL) ``` Men: 107 – 120 mL/min Women: 87 – 107 mL/min

Question 26

Fanconi Syndrome Macroscopic Microscopic

Answer 26

Macroscopically-Elevated Protein, Elevated Glucose, normal serum glucose Microscopically-cystine crystals

Question 27

List the common findings with fanconi syndrome

Answer 27

Most common disorder associated is tubular dysfunction. Generalized failure of tubular reabsorption in the proximal convoluted tubule.

Question 28

Cystinosis Pathogenesis Symptoms/Treatment Urinalysis

Answer 28

Pathogenesis: intracellular deposition of cystine. Symptoms/Treatment: Patients are unable to concentrate or acidify urine, results in growth retardation, rickets, acidosis, polydipsia, and polyuria. Patients must undergo dialysis or transplant. Urinalysis: Hematuria, proteinuria, increased RBCs and cystine crystals.

Question 29

Cystinuria Pathogenesis Urinalysis

Answer 29

Pathogenesis: Inability of the renal tubules to reabsorb cystine filtered by the glomerulus. Urinalysis: Hematuria, proteinuria, increased RBCs and cystine crystals.

Question 30

Cystinosis Pathogenesis Symptoms/Treatment Urinalysis

Answer 30

Pathogenesis: Genuine inborn error of metabolism. Fanconi’s syndrome occurs Symptoms/Treatment: In severe cases, gradual progression to renal failure. Urinalysis: polyuria, generalized aminoaciduria and lack of urinary concentration.

Question 31

Homocystinuria Pathogenesis Symptoms/Treatment Urinalysis

Answer 31

Pathogenesis: Defects in homocystine metabolism. Symptoms/Treatment: In severe cases, gradual progression to renal failure. Urinalysis: Gives a positive cyanide-nitroprusside test. Must be confirmed with silver-nitroprusside test in which only homocystine reacts.

Question 32

Osmolarity

Answer 32

Can be determined by measuring the colligative properties of the solution and comparing this value with the value obtained from the pure solvent. Major uses of osmolarity includes includes renal concentrating ability, monitoring the course of renal disease, monitoring fluid and electrolyte therapy. Normal serum 275-300 mOsm. Normal urine 50-1400 mOsm.

Question 33

Free Water Clearance

Answer 33

The free water clearance is determined by first calculating the osmolar clearance using the standard clearance formula of COSM = (Uosm x V) / Posm and then subtracting the osmolar clearance value from the urine volume in mL/minute. Calculation of the osmolar clearance tells how much water must be clear each minute

Question 34

Specific gravity

Answer 34

Depends on the # of particles present in a solution and the density of these particles. When evaluating renal concentrating ability, the substances of interest are small molecules, primarily sodium and chloride, but urea influences the specific gravity more than sodium or chloride.

Question 35

Acute Tubular Necrosis Pathogensis Urinalysis

Answer 35

Pathogenesis: Primary disorder associated with damage to the renal tubules. Caused by shock, trauma, and surgical procedures. Variable disease course. Urinalysis: Urinalysis findings include mild proteinuria, microsocopic hemaoturia, and presence of renal tubular epithelial cells and casts, and other casts including hyaline, granular, waxy and broad.

Question 36

Renal tubular acidosis | Pathogenesis:

Answer 36

Pathogenesis: Due to inability to secrete adequate hydrogen ions, patients are unable to acidify urine, Inherited autosomal dominant trait.

Question 37

Diabetes Mellitus Macroscopically Microscopically

Answer 37

Macroscopically-Elevated glucose and ketones Microscopically-unremarkable. Proteins, glucose, ketones

Question 38

Discuss other carbohydrates that maybe elevated in the urine. Indicate the significance of elevated galactose

Answer 38

Presence of galactosuria indicating the inability to properly metabolize galactose to glucose. Laboratory testing involves detection of non-glucose related reducing substances.

Question 39

Compare and contrast type 1 diabetes mellitus and type 2 diabetes mellitus.

Answer 39

Type 1 usually present before the age of 40 the unset is usually sudden. The glucose is elevated because of a lack of insulin production. Type 2 diabetes presents after the age of 40 is usually a slow on set and is often the result of obesity.

Question 40

Explain the role of the kidney in acid base balance

Answer 40

Homeostasis: Regulate Acid-Base Balance by maintaining blood pH at normal values (7.35-7.45). Acidotic Conditions: H+ ions are secreted in exchange for sodium and bicarbonate ions. Alkalotic Conditions: H+ ion secretion minimized, additional alkali ions are secreted.

Question 41

Erythropoietin

Answer 41

Hormone produced by the kidneys in response to tissue hypoxia to stimulate the production of RBCs thereby increasing amount of oxygen carried to the tissues

Question 42

Prostaglandin

Answer 42

Hormone produced by the renal medulla, increases the renal blood flow and the excretion of salt and water

Question 43

Renin

Answer 43

Ultimately stimulates the production of aldosterone, which regulates sodium and potassium and water secretion.

Question 44

Angiotensin II

Answer 44

A vasoconstrictor that reduces the glomerular filtration rate and stimulates the production and release of aldosterone

Question 45

Aldosterone

Answer 45

Basic function is to stimulate the kidneys to retain or secrete sodium and potassium ions. When total blood volume is decreased, sodium and water are retained, if serum potassium is elevated, more potassium is excreted which in turn increases arterial pressure

Question 46

ADH: (Antidiuretic hormone)

Answer 46

ADH (vasopressin) alters the permeability of the distal tubule and collecting duct. When blood volume is decreased, ADH secreted which causes an increase in water reabsorption and when blood volume is increased, ADH secretion is inhibited, more water is excreted.

Question 47

Discuss the renin-angiotensin-aldosterone system

Answer 47

When the juxtaglomerular apparatus senses change it activates the rennin-angiotensin-aldosterone system. Renin, which is produced by the juxtaglomerular apparatus, is secreted and reacts with the bloodborne substrate angiotensiongen to produce angiotensin I. As angiotensin I passes through the lungs it is converted to angiotensin II.

Question 48

Nephrolithiasis

Answer 48

Disease process involving the formation of stones, most common is calcium mixed with oxalate or phosphate. Involves changes in urine pH, increased urine stasis, presence of foreign body deposits in urinary tract.

Question 49

Phenylketonuria

Answer 49

Caused by a failure to inherit the gene to produce phylalanine hydroxylase. Most common is aminoacidurias. Initially diagnosed with a blood test shortly after birth. Urine test is used a screening test to ensure proper dietary intake

Question 50

Alkapturia

Answer 50

Occurs from the failure to inherit the gene to produce the enzyme homogentisic acid oxidase. Without the enzyme, homogentisic acid accumulate in the blood, tissues, and urine. Urine darkens upon standing.

Question 51

MSUD: Maple Sugar Urine Disease

Answer 51

Caused by an inborn error of metabolism. Failure to inherit the gene for the enzyme necessary to produce oxidative decarboxylation of these keto acids result in the accumulation of ketoacids. Most frequent screening test for detection of keto acids is the 2,4 dinitrophenylhydrazine (DNPH) reaction. Adding DNPH to urine that contains ketoacids will produce a yellow turbidity or precipitate

Question 52

Melanuria

Answer 52

Increased production of melanin leads to a darkening of urine. Elevation of urinary melanin is a serious finding that indicates the over proliferation of the normal melanin-producing, producing a malignant melanoma.

Question 53

Homocystinuria

Answer 53

Defects in homocystine metabolism. Gives a positive cyanide-nitroprusside test. Must be confirmed with silver-nitroprusside test in which only homocystine reacts.