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Urinalysis and Body Fluids 4214 > Exam 1: Lectures 3 & 4 > Flashcards

Exam 1: Lectures 3 & 4 Flashcards

1
Q

What are the three systems that are used to maintain acid-base balance in the body?

A

-Blood buffer systems (Hemoglobin, proteins, inorganic phosphates)
-Pulmonary system (exhaling CO2 acid)
-Renal system (increase or decrease reabsorption of bicarbonate, excretion of H ions, formation of ammonia)

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2
Q

In acidic blood conditions, H+ ions are secreted in exchange for _________ and __________.

A

sodium, bicarbonate ions

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3
Q

In acidotic conditions, ammonia diffuses into the tubular lumen and subsequently ________ ions are reabsorbed while ammonium ions are excreted

A

sodium

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4
Q

In alkalotic blood conditions, tubular secretion of what is minimized?
and what is secreted more?

A

H+, bicarbonate

ammonia then combines with hydrogen ions to form ammonium ions in the tubular lumen to help regulate the (H+) concentration of urine.

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5
Q

Hydrogen ions are produced as waste from metabolism and are generally __________.

A

secreted

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6
Q

Bicarbonate can also be secreted but is more often reabsorbed, (usually up to _____ %) to help maintain the proper blood pH.

A

100

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7
Q

True or False?

The kidney plays the major role in metabolic acidosis, metabolic alkalosis, and in the compensation of respiratory acidosis or alkalosis.

A

true

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8
Q

What cells produce Renin?

A

juxtaglomerular cells

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9
Q

What reacts with the precursor angiotensinogen in the blood to produce angiotensin I?

A

Renin

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10
Q

Where is angiotensin I converted to angiotensin II?

A

in the lungs

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11
Q

How does the renal system control blood pressure?

A

at the juxtaglomerular apparatus by constriction of afferent arterioles under the control of renin

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12
Q

an enzyme produced by the juxtaglomerular cells, is secreted and reacts with the precursor angiotensinogen in the blood to produce angiotensin I.

A

Renin

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13
Q

Angiotensin I passes through the lungs where the enzyme ____________ changes it to the active angiotensin II.

A

angiotensin converting enzyme (ACE)

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14
Q

What are ACE inhibitors used to treat?

A

high blood pressure

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15
Q

What effect does angiotensin II have?

A

-vasoconstrictor (corrects blood flow in the efferent arterioles)
-stimulates the release of aldosterone (to retain Na and excrete K+)
-triggers release of ADH (vasopressin)

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16
Q

What happens when blood pressure is high or potassium decreases?

A

-renin is inhibited
-angiotensin inhibited
-sodium is excreted

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17
Q

Angiotensin II corrects renal blood flow by _________ the afferent arteriole and __________ the efferent arteriole, by stimulating sodium reabsorption in the proximal convoluted tubule

A

dilating, constricting

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18
Q

If water conservation is not needed, ADH is not secreted and the duct remains ___________ to water. the result is dilute urine.

A

impermeable

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19
Q

If the body becomes dehydrated, what does ADH do at the distal tubule and collecting ducts?

A

increases water permeability

Water diffuses into surrounding fluids (reabsorbed) resulting in concentrated urine.

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20
Q

______ enhances countercurrent multiplication and urea cycling by increasing transport of Na+ in LH

A

ADH

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21
Q

The ascending loop is impervious to water but actively recovers _____ reducing filtrate osmolarity to ______ mOsmol/kg.

A

Na+, 50-100

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22
Q

The descending and ascending loop and vasa recta form a countercurrent multiplier system to increase ________concentration in the kidney medulla.

A

Na+

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23
Q

Nearly ____ percent of water is recovered before the forming urine reaches the DCT, which will recover another ____ percent.

A

90, 10

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24
Q

_______ and __________ are involved in the regulation of blood pressure

A

Renin, angiotensin

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25
Q

In the collecting ducts, ADH stimulates _________ channel insertion to increase water recovery and thereby regulate osmolarity of the blood. Aldosterone stimulates Na+recovery by the collecting duct.

A

aquaporin

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26
Q

What are the two ways filtration can be indirectly estimated?

A

-classic clearance tests using a surrogate
-eGFR using serum creatine

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27
Q

Why is eGFR used instead of clearance tests?

A

Clearance tests slightly overestimate GFR so eGFR is more commonly used.

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28
Q

For clearance tests, the surrogate has to be…

A

-endogenous preferred
-completely filterable from plasma
-not be secreted by the renal tubules
-not be reabsorbed by the renal tubules

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29
Q

Test that measures the rate at which the kidneys can remove a filterable substance from the blood

A

clearance tests

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30
Q

We measure glomerular filtration rate (GFR) by comparing creatinine level urine collected over 24 hours compared to that of…

A

blood

31
Q

What are the reported units for GFR?

A

ml/min

32
Q

How is the creatinine clearance test preformed?

A

-pt collects urine for 24 hours
-draw blood and test for creatinine levels
-obtain height and weight info
-use GFR formula

33
Q

Kidney damage is associated with a GFR of less than ____.

A

60

34
Q

How many stages of chronic kidney disease are there?

A

5 (5 being the worst)

35
Q

Creatinine is produced as a result of ________ destruction.

A

muscle

36
Q

Men clear creatinine at a rate of _______ mL/min and women clear at a rate of ______ mL/min

A

110 to 150 mL/min

100 to 130 mL/min

37
Q

Normal reference range of plasma creatinine?

A

0.5 to1.5 mg/dL

38
Q

GFD decreased with….

A

age

39
Q

Many medications must be adjusted for when renal impairment that is below ____mL/min

A

50

40
Q

What is the standard clearance formula?

corrected clearance formula?

A

C = U * V / P

C = [U * V / P] x [1.73m^2/body surface area)

U = urine concentration
P = plasma concentration
V = volume of urine excreted

41
Q

Using the Dubois equation, how is body surface area calculated?

A

BSA (m2) = 0.007184 x Height(cm)^0.725x Weight(kg)^0.425

42
Q

The best overall index of kidney function is?

A

GFR

43
Q

Why is the Cockcroft-Gault (CG) formula not recommended for clinical use.

A

formula has not been expressed using standardized creatinine values and it will give inaccurate results

44
Q

The National Kidney Foundation recommends using the __________ Equation (2021) to estimate GFR.

A

CKD-EPI Creatinine

45
Q

What is the CKD-EPI Creatine Equation (2021)?

A

eGFRcr = 142 x min(Scr/κ, 1)α x max(Scr/κ, 1)-1.200 x 0.9938Age x 1.012 [if female]

Scr = standardized serum creatinine in mg/dL
κ = 0.7 (females) or 0.9 (males)
α = -0.241 (female) or -0.302 (male)
min(Scr/κ, 1) is the minimum of Scr/κ or 1.0
max(Scr/κ, 1) is the maximum of Scr/κ or 1.0

46
Q

What are the limitations of GFR calculations?

A

-Overestimates GFR by about 10%
-Tubular secretion increases with high blood creatinine levels
-Gentamicin, cephalosporins, and cimetidine inhibit tubular secretion
-Bacteria break down creatinine if urine is stored at room temperature
-Diet heavy in meat during timed collection increases urine creatinine
-Accurate results depend on the accurate completing of a 24-hour collection
-It must be corrected for smaller/larger body surface area

47
Q

What method does not require urine collection and is used for long term monitoring?

A

Cystatin C

-test uses anti-cystatin antibodies

48
Q

Small protein produced by all nucleated cells; filtered by glomerulus

A

Cystatin C

49
Q

Why is cystatin C used for assessing renal function?

A

Absorbed and catalyzed by the renal tubules and broken down; no cystatin C is secreted. Levels in the blood remain at a constant level. When GFR is decreased, cystatin c levels are increased in blood.
-Serum levels directly reflect GFR

50
Q

What test is essential for monitoring renal disease progression?

A

Cystatin C

51
Q

Cystatin C is used to determine….

A

drug dosages and evaluating uremia

52
Q

Normal range for Cystatin C?

A

0.51 - 0.98 mg/L

53
Q

Beta2 microglobulin test can be run on what type of samples?

A

urine and/or serum

54
Q

Small protein that dissociates from human leukocyte antigens at a constant Reabsorbed completely in normally functioning kidney but shows up in urine when tubular reabsorption is impaired.

A

Beta2 microglobulin

55
Q

sensitive indicator of a decrease in GFR

A

Beta2 microglobulin

56
Q

What can the Beta2 microglobulin test determine?

A

Indicates kidney transplant rejection or people with impaired or distinguishes tubular damage from glomeruli dysfunction.

57
Q

Beta2 microglobulin:

If high in urine but normal in serum:

If high in blood but low in urine:

A

tubular dysfunction

glomeruli dysfunction

58
Q

____________ appears early in diabetic nephropathy and persons with high blood pressure.

A

Albuminuria

59
Q

What causes the presence of albumin in urine?

A

increased glomerular permeability due to changes in glomerular filtration barrier

60
Q

What should be done if there is early detection of microalbuminuria?

A

additional testing and aggressive intervention

61
Q

A microalbumin to creatinine ratio of ____ mg/g is considered diagnostic of microalbuminuria.***

A

greater than 30

(albumin/creatine)

62
Q

Why is the urine dipstick an insensitive marker for albuminuria?

A

will not be positive till it exceeds 300 to 500 mg/day.

using a specific assay for albumin is a more sensitive technique.

63
Q

What is the normal rate of albumin excretion?

A

less than 30 mg/day

64
Q

What albumin excretion levels is moderately increased albuminuria?

A

30-300 mg/day

65
Q

How is ACR calculated?

A

ACR is calculated by dividing albumin concentration in milligrams by creatinine concentration in grams.

Have to use g/dL creatinine, not mg/dL

66
Q

Why would a physician want to assess tubular function?

A

to test the ability to reabsorb substances and concentrate urine.

67
Q

What is the SG of urine just after filtration?

A

1.010

68
Q

Why would the specific gravity remain fixed at 1.010 regardless of water intake or hydration level?

A

Patients with loss of tubular function lose the ability to adjust the filtrate.

(the first a.m. specimen will be the same as the last p.m. specimen)

69
Q

Tubular reabsorption tests are a good indicator of…

A

early renal disease

Measure renal concentrating ability
(Salts and water)

70
Q

What are tubular reabsorption tests often termed?

A

concentration or fluid deprivation tests

71
Q

What are two tests used to measure concentration?

A

-specific gravity
-osmolality

(non-specific, but good for screening)

72
Q

normal range for specific gravity?

A

1.003 to 1.035

73
Q

What is one of the first functions to be lost as result of tubular damage?

A

the concentrating ability of the kidney

Urinalysis and Body Fluids 4214 (14 decks)

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