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Lab Dx 1 > week 4: renal and RBC morphology > Flashcards

week 4: renal and RBC morphology Flashcards

1
Q

• What is urine calcium used for?

A

o To determine primary hyperparathyroidism; cause of recurrent nephrolithiasis
o Increased levels: hyper pth, vit d excess, corticosteroid, cushing’s, sarcoidosis, osteoporosis, bone tumor, renal tubular acidosis
o Decreased: hypo pth, vit D def, Ca malabsorption, renal failure

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2
Q

• What are constituents of most kidney stones?

A

o Calcium oxalate: low urine vol

o calcium phosphate: alkaline urine

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3
Q

• When is 24 hr oxalate indicated?

A

o Surgical loss of distal ileum, esp crohn’s
o IBS
o Jejunal bypass
o Excess enteric fat

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4
Q

• What are normal 24 hr oxalate values?

A

o Males: 7-44 mg
o Female: 4-31
o Child: 13-38

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5
Q

• What causes increased/decreased oxalate?

A

o Increased: ethylene glycol, genetic (hyperoxaluria), pancreas dz, liver cirrhosis, pyridoxine def (B6), sarcoidosis, celiac
o Decreased: renal failure, high urinary Ca

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6
Q

What is hypocitraturia?

A

o 24 hr urine: <400-500 (F and M)
o Decreased by: IBD, intestinal malabsorption, renal tubular acidosis
o High protein diet cause decreased citrate
o Citrate normally inhibits Ca crystals

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7
Q

• What is 24 hr urine uric acid?

A

o Normal: 25-750 mg
o From purine metabolism; made in liver
o 75% in blood excreted by kidneys, rest by GI
o Elevated= gout
o Stones in urine with very low pH (10-15% of stones)

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8
Q

• What can cause increased and decreased urine uric acid?

A

o Uricosuria: gout, cancer, myeloma, leukemia, chemo, high purine diet, lead
o Decreased: renal dz, eclampsia, alcoholism

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9
Q

• What are triple phosphate crystals?

A

o Mg NH4 PO4; alkaline urine
o More common in women; UTIs from bacteria
o Form struvite stones (10-15% of stones)

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10
Q

• What is 24 hr vanillylmandelic and homovanilic acid?

A

o End products of catecholamines

o Dx pheochromocytoma, neuroblastoma, ganglioneuroma

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11
Q

• Instructions for 24 hr urine collection?

A

o Urinate in morning, start time, collect next 24 hrs

o Keep refrigerated

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12
Q

• What is deoxypyridinoline and bone turnover?

A

o Cross-link of collagen- tensile strength to bone matrix
o In blood from bone resorption, into urine
o Also found in dentin, be very careful not to contaminate
o 2nd morning void best

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13
Q

• What causes increased deoxypyridinoline?

A

o Osteoporosis, bone cancer, hyperthyroid, children, hyper PTH, myeloma, steroids, cushings

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14
Q

• What is N-telopeptides (ntx) in bone turnover?

A

o Decreases with age; cross links in collagen

o Similar to deoxypyridinoline

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15
Q

• What is urinary human chorionic gonadotropin (HCG)

A

o Pregnancy dx, and some cancers (germ cell tumors)

o Serum levels increase first, 10 days after conception to see in urine

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16
Q

• Increased HCG?

A

o Hydratidiform mole: abnormal pregnancy

o Choriocarcinoma: malignant placental epithelium

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17
Q

• When is drug testing done clinically?

A

o Before prescribing a medication/controlled substance
o Before increasing dose
o Before referring to pain or addiction specialist

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18
Q

• What are 2 main types of urine drug test?

A

o Immunoassay: Abs, rapid results, cheap, preferred, high PPV for pot and cocaine; low PPV for opiates and amphetamines
o GC/MS: molecules separated, expensive, more accurate (used in forensics)

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19
Q

• How long can immunoassay detect drugs?

A

o Most are1-3 days

o Pot is increased with increased use

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20
Q

• What gives false negs for immunoassay?

A 
o	Dilute urine
o	Past time detection of use
o	Lab’s established threshold limits
o	Sample tampering
o	Neg result doesn’t exclude occasional or even daily use
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21
Q

• What gives false pos with immunoassay?

A

o Welbutrin, Prozac, pseudephedrine, Ritalin, benadryl, poppy seeds, ibuprofen, Demerol, NSAIDs, PPIs

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22
Q

• Criteria for drug urine test? Adulteration?

A

o At least 30 mL
o 90-100 F
o Ph=4.5-8.5
o Tamper: nitrite >500 mg/dL, unusual appearance, very low sp grav

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23
Q

• What is hematology?

A

o The science concerned with blood & blood forming tissues

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24
Q

What is the complete blood count?

A

o most routinely run panel in the health care system.
o inexpensive and often included as part of a routine health screening.
o Includes information about RBCs, WBCs, Platelets, Nutritional status, Inflammation, Many specific disease states, Hydration, Occult blood loss, And much more…

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25
Q

Describe the RBC:

A

o compose 99% of cells in blood
o Each second, 2-3 million RBCs are created and destroyed
o Biconcave disk allows for increased surface area and flexibility
o 7 µm in diameter, but can squeeze though capillaries as small as 3 µm wide
o Does not contain a nucleus in order to make room for hemoglobin (a protein oxygen carrier)
o Central area appears pale due to a decrease in hemoglobin

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26
Q

• What is the function of RBCs?

A

o A flexible “container” for hemoglobin (Hgb)
o Gas exchange, transport & release of oxygen (ATP) & carbon dioxide.
o Contributes to buffering capacity of blood – carbonic anhydrase enzyme catalyzes: CO2 + H2O -> H2CO3 -> dissociates H+ + HCO3 (bicarbonate).
o Hgb also acts as a buffer by picking up the H+, to maintain blood pH at 7.35-7.45
o Clotting mechanism role via formation of a hemostatic plug.

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27
Q

• In what forms are CO2 transported?

A

o Dissolved CO2; Hb; HCO3-

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28
Q

• What is erythropoietin (EPO)?

A

o Glycoprotein hormone produced by the kidney.
o Acts on bone marrow stem cells to increase production of RBCs
o In turn, production of EPO is regulated by the oxygen levels detected in the kidney
o Can be tested for in serum as a cause of polycythemia (increased # of RBCs) or anemia
o Reference Range: 2.6-18.5 mU/ml

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29
Q

• What can cause elevated EPO?

A

o Responding to decreased O2 states: high alt, COPD, heart dz, smoking, any hypoxic event
o Improper excretion: renal CA, hepatic CA, adrenal CA

30
Q

• What can cause decreased EPO?

A

o Renal failure; increased IL-1 or TNF (AD, HIV, chronic infection); severe malnutrition; hypothyroid; malignancy

31
Q

• What is erythropoiesis?

A

o RBC production: series of consecutive events where a primitive stem cell matures into a functional erythrocyte. In adults this normally occurs only in the bone marrow of long or flat bones.

32
Q

• What are the hematopoietic organs during fetal development?

A

o 1st trimester: widespread in mesenchyme
o 2nd: liver and spleen
o 3rd: bone marrow

33
Q

• How does RBC maturation occur?

A

o Undifferentiated stem cell (in BM) acted on by colony stimulating factor -> Rubriblast -> Prorubricyte -> Rubricyte (hemoglobin production initiated) ->
o MATURATION= Metarubricyte -> looses nucleus & becomes Reticulocyte -> released into circulation and matures in about 24 hours ->
o Erythrocyte = mature RBC (lives 120 days)

34
Q

• What is an erythroblastic island?

A

o Niche for erythropoiesis

o In BM: erythroid precursors surrounding a central “nurse” macrophage

35
Q

• What are reticulocytes in circulation? Ratio to RBCs?

A

o Reticular in Latin is “net”
o Easy to identify under the microscope due to their mesh like and bluish appearance (ribosomal RNA), with Wright stain
o Larger in size than more mature RBCs
o Normal ratio of retics to mature RBC’s is 0.5%-1.5%

36
Q

• How long are reticulocytes in circulation?

A

o Lives in circulation for ≈24 hours until becoming a mature RBC (in non-anemic ppl)
o Anemic: Retic maturation time increased in proportion to the severity of the anemia (up to 2.5 days).

37
Q

• What reticulocyte counts may be expected? What does Anemia with low reticulocytes indicate?

A

o Should expect to see an increase when body is responding to an anemia or hemorrhage (reticulocytosis).
o Failure of bone marrow –Aplastic anemia
o EPO deficiency –Renal failure
o Bone marrow malignancy –Leukemia
Anemia of chronic disease

38
Q

What are interfering factors with reticulocyte counts?

A

o Pregnancy – may see increased count secondary to increased fluid volume, hypoxia
o Howell-Jolly bodies (DNA nuclear remnant) may be miscounted by techs or machines as reticulocytes

39
Q

• What is the reticulocyte index?

A

o Recommended for anemia
o The relative percentage of reticulocytes may increase if the reticulocytes are increased or the RBCs are decreased
o RI corrects for this; adjusts for pts’s hematocrit compared to normal level
o RI= ret% x HCT / .45 (standard HCT)

40
Q

• What are normal and bad RIs?

A

o patients with good marrow responses to anemia should be 2-3% indicating increased RBC production.
o RI < 2.0%, even with elevated retic counts, the response is inadequate, hypoproliferative
o Bone marrow may not respond adequately to compensate for anemia, despite apparently elevated retic count

41
Q

• What are the 3 types of pathologic RIs?

A

o Hypoproliferative: when RI3-5, normocytuc (blood loss, etc)

42
Q

• What can cause increased reticulocyte levels (reticulocytosis?

A

o Hemolytic anemia; hemorrhage; HDN (hemnolytic dz of the newborn); treated deficiency anemias

43
Q

• What can cause decreased reticulocyte levels (reticulocytopenia)?

A

o Pernicious anemia; nutrient deficiencies; anplastic anemia; radiation therapy; marrow failure; chronic dzs

44
Q

• What are two mays of counting RBCs?

A

o Manual: count a diluted sample on slide, under HPF microscope
o Coulter counter: takes 1/3 time, 10x more accurate, 1st commercial machine

45
Q

• How does the coulter counter work?

A

o Detects the size of particles using the difference in resistance between a particle and the surrounding fluid: each drop in current counts as a particle
o Volume displaced is measured in voltage. The height of each voltage reading is proportional to the volume of the cell.
o Conducting liquids are used, with electrodes

46
Q

• What are the benefits of the coulter counter?

A

o The quantity of blood & solution suspension drawing RBC’s through the aperture is precise & reproducible.
o Several thousand cells per second are individually counted & sized with great accuracy.
o RBC Counts reported as million/mm3
o This method is independent of cell shape, color & density.
o Automated RBC counts allow Hematocrit calculation

47
Q

• What are the reference ranges for RBC counts by age and sex?

A 
o	Men: 4.2-5.4
o	Women: 3.6-5.0
o	Birth-8 weeks: 4.0-6.1
o	2-6 months: 3.8-5.6
o	6 mos to 1 yr: 3.8-5.2
o	1-6 yrs: 3.9-5.3
o	6-16 yrs: 4.0-5.2
o	16-18 yrs: 4.2-4.5
48
Q

• What are reasons for increased RBCs (based on EPO levels)

A

o Low EPO: primary polycythemia (genetic d/o)
o Normal EPO: bone marrow proliferative d/o (leukemia, etc); dehydration (reduced plasma to RBC ratio)
o High EPO: renal proliferative d/o; secondary polycythemia (high alt or pulmonary d/o)

49
Q

• What can cause decreased RBCs (erythrocytopenia, anemia)

A

o Malnutrion, malabsorption, inflammation, hemorrhage, hemolytic, BM failure, renal dz, etc

50
Q

• What are interfering factors for RBC counts?

A

o Pregnancy shows decreased counts secondary to plasma volume increase; also nutritional deficiencies (Fe deficiency anemia)
o High altitude increased count due to hypoxia (“Reactive Polycythemia”)
o Hydration status can increase or decrease
o Drugs that raise: Gentamycin, methyldopa
o Drugs that lower: Chloramphenicol, quinidine

51
Q

• What is hematocrit? How is the value found?

A

o The portion of blood composed of erythrocytes. Aka packed cell volume (PCV)
o Usually 3x the Hb
o Expressed as a percentage of the total blood volume (indirect measure)
o After whole blood is centrifuged, the RBCs will collect at the bottom of the tube.
o The value is determined by dividing the height of the erythrocytes by the total height of the blood in the tube and multiplying by 100.

52
Q

• What is calculation for Hct? Reference ranges? What does I mean?

A

o Hct= MCV x RBC / 10
o M= 42-52%
o F= 37-47%
o Ex: 40.5% blood is RBC volume; 59.5% plasma and other elements

53
Q

• What is anisocytosis?

A

o Any significant variation in size of RBC
o Found in most anemias and leukemias
o Results from abnormal cell development
o Often due to deficiency in raw material (i.e. iron, B12, folic acid)
o Graded on a scale of 1+ to 4+
o Variation corresponds with RDW (RBC Distribution Width)

54
Q

• What is RDW?

A

o Statistical measure of variation in RBC size
o Calculated from MCV & RBC
o An indicator of the degree of anisocytosis
o RDW histogram (essentially a distribution graph) allows visualization of differing RBC populations

55
Q

• What do changes in RDW mean? Normal values?

A

o Increase: have clinical significance; iron deficiency anemia; B12 or folic acid deficiency anemia; hemoglobinopathies; hemolytic anemias; posthemorrhagic anemia
o Decreases: NOT clinically significant
o Normal adult values: 11.5-14.5

56
Q

• What are macrocytes? Shapes?

A

o Increased RBC cell size (macrocytic)
o > 8 um
o Well hemoglobinized (lacks a central pallor)
o Round: liver dz
o Oval: B12/folic acid def; pernicious anemia

57
Q

• What are microcytes?

A

o < 6 um
o Increased central pallor, less Hb
o Fe def, blood loss, sideroblastic

58
Q

• What is a peripheral smear evaluation?

A

o Inexpensive and powerful diagnostic tool.
o Used to determine if cells appear normal in size, shape, and count
o Not required in all pts, but helpful in diagnosing a range of deficiencies, diseases and disorders involving production, function and destruction when the CBC gives an incomplete picture.

59
Q

• What is poikilocytosis?

A

o Excessive variation in normal RBC shape (n=doughnut)

o Pathologies can cause distortions in normal RBC shape, which may affect proper RBC function

60
Q

• What are “target cells” (codocytes)? Causes? Tests?

A

o Dark center & periphery separated by pale area (normal area of pallor has color spot in center)
o Due to increase in RBC surface membrane from excess cholesterol and phospholipids and decreased cellular HB
o Thalassemia; Splenectomy; Liver disease; Iron deficiency; Hemoglobinopathies; Decreased osmotic fragility
o Test to follow up with: CBC with differential, iron studies, liver profile testing

61
Q

• What are spherocytes? How do pts present? Causes?

A

o “Sphere or globe” with dense appearance (no central pallor), increased hemoglobin content, increased thickness of the cell and often a decrease in diameter
o Burst more readily when exposed to osmotic pressure due to increased osmotic fragility
o Shorter life span. In AI hemolytic anemia, cell surface is coated with antibodies causing decrease cholesterol, decreasing surface area, but not decreasing hemoglobin. More fragile.
o Patients present with anemia, splemomegaly and jaundice.
o Causes: autoimmune hemolytic anemia, hereditary spheroytosis

62
Q

• What are schistocytes? Causes?

A

o Fragmented RBCs; aka “bite cells”
o Resulting from some form of trauma to the membrane
o Causes: Artificial heart valve; Hemolytic uremic syndrome (HUS); Disseminated intravascular coagulation (DIC); Thrombotic thrombocytopenic purpura (TTP); microangiopathic hemolytic anemia; severe burns; uremia;

63
Q

• What are helmet cells?

A

o Also aka bite cells
o Have 2 distinct projections
o Seen in cases with large inclusion bodies (Heinz, Howell Jolly)
o Spleen tries to remove inclusion and takes a bite out of cell.

64
Q

• What are echinocytes?

A

o Multiple tiny spicules (10-30) evenly distributed over the cell surface.
o Result from exposure of certain substances to the cell surface; and change in tonicity in intravascular fluid (dehydration, azotemia)
o Also known as burr cells; crenated RBCs
o Characteristically seen in uremia.
o Can also happen from faulty drying of the blood smear

65
Q

• What are acanthocytes (spur cells)?

A

o Spheroid RBCs with a few large thorny projections.
o Usually 5-10 spicules per cell. Hard to differentiate from echinocytes (shorter and more regular spicules).
o Seen in: Post splenectomy; Alcoholic cirrhosis; Various hemolytic anemias

66
Q

• What are dacrocytes?

A

o Teardrop shaped cells can be seen in meylofibrosis with myeloid metaplasia.
o pathologic and usually indicate significant bone marrow failure.
o seen in moderate numbers with: Megaloblastic anemia; Renal failure; Severe iron deficiency; Thalassemia major; some hemolytic anemias

67
Q

• what are elliptocytes?

A

o Also known as ovalocytes
o normally comprise less than 1% of total RBCs.
o Numbers can increase up to 10% in cases of thalassemia or deficiencies of iron or folate.
o In cases of hereditary elliptocytosis, nearly all of the cells may be ovoid

68
Q

• What are sickle cells? Effect on spleen?

A

o Abnormal hemoglobin SS is prone to crystallization when oxygen tension is low, RBCs change shape into long thin sickle forms that get stuck in capillaries, further decreasing blood flow and oxygen tension.
o Patients may start out with splenic enlargement, but eventually (by early adolescence) the spleen size has been tremendously reduced in size due to continual stasis and infarctions.

69
Q

• What are the common RBC inclusion?

A 
o	Howell jolly bodies; DNA
o	Heinz bodies; Hb
o	pappenheimer bodies; iron deposits
o	Hb  H inclusion; Hb
o	basophilic stippling: ribosomes
70
Q

• what are Howell-jolly bodies?

A 
o	Small (1 um) inclusions of nuclear chromatin remnants or fragments. Most often present post splenectomy, because the spleen would naturally remove these RBCs from circulation
o	Also seen during increased production of RBCs, following cell destruction, such as in hemolytic anemia

Lab Dx 1 (8 decks)

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