Laboratory Module

Question 1

Hypernatremia

Answer 1

Cause: Impaired thirst mechanism
Uncontrollable water loss

Symptoms: Hyperreflexia, muscle twitching,
thirst, irritability, coma, death

Useful in determining the fluid balance and maintaining the appropriate transmembrane electrical potential in neuromuscular function

Question 2

Hyponatremia

Answer 2

Severe dehydration
Water intake > output
DRUGS

Depressed reflexes, disorientation, muscle cramps, nausea

Also related to Neuromuscular function

Question 3

K (potassium ions)

Answer 3

Responsible for the control of intracellular volume ; also related to protein synthesis, enzymatic reactions and carbohydrates metabolism

Question 4

Hyperkalemia

Answer 4

Increased intake (Drugs, hemolysis, muscle damage, burns)
 Decreased output (Renal Failure, drugs)
 Extracellular shift (metabolic acidosis)

Arrythmias, hypotension, weakness, bradycardia, cardiac arrest

Question 5

Hypokalemia

Answer 5

• *Decreased intake** (alcoholism, diets low in K, eating disorders)
• *Increased output** (drugs, laxatives, vomiting and diarrhea, Cushing syndrome)
• *Intracellular shift**: insulin administration ; alkalosis

Arrythmias, hypotension, weakness, muscle cramps

Question 6

Hyperchloremia

Answer 6

Dehydration, acidemia

Limited to underlying disorder

Related to acid-base balance

Question 7

Hypochloremia

Answer 7

Vomiting, alkalemia

Limited to underlying disorder

Question 8

Hypermagnesemia

Answer 8

Over-repletion
Renal dysfunction

Bradycardia, sweating, hypocalcemia, drowsiness

Question 9

Hypomagnesemia

Answer 9

Renal wasting
Alcohol abuse
Malnutrition
Diarrhea

Weakness, tremors, tetany,
Increased reflexes

Question 10

Hypercalcemia

Answer 10

Malignancy
Hyperparathyroidism

Gastrointestinal complaints, neuromuscular symptoms

Question 11

Hypocalcemia

Answer 11

DRUGS
Vitamin D deficiency
Hypoparathyroidism

Fatigue, memory loss, hallucinations, seizures, tetany

Question 12

Hyperphosphatemia

Answer 12

Decreased excretion
Increased intake
Extracellular shift

Signs and symptoms of hypocalcemia and hyperparathyroidism

Question 13

Hypophosphatemia

Answer 13

Increased excretion
Intracellular shift
Alcoholism
Malnutrition

Irritability
 CNS effects (drowsiness, difficulty thinking or cognition)

Question 14

Hyperglycemia

Answer 14

Diabetes
Diet
DRUGS

Thirst (Polydipsia)
Urination (Polyuria)

Question 15

Hypoglycemia

Answer 15

DRUGS

Sweating, trembling, palpitations, headache, confusion

Question 16

SCr

Answer 16

is an endogenous marker of renal function

i. Inverse relationship with renal function
ii. Affected by: muscle mass, sex, age, race, drugs, assays, low-protein diets
iii. Reference range vs baseline

Question 17

BUN

Answer 17

is used to assess or monitor hydration, renal function, and protein tolerance

Question 18

BUN

High

Causes and Symptoms

Answer 18

High protein diet

Upper GI bleeds

DRUGS

Greater than 100mg/dL: high risk of uremic syndrome

Limited to underlying disorders

Question 19

BUN

LOW

Causes and Symptoms

Answer 19

Malnourishment

Liver damage

Fluid overload

Limited to underlying disorders

Question 20

BUN:Scr ratio

Answer 20

BUN:Scr ratio > 20:1 and elevated

Pre-renal causes: dehydration, blood loss, shock, severe heart failure

10:1 to 20:1 Intrinsic causes

Acute: drugs, severe hypertension, tubular necrosis Chronic: diabetes, pyelonephritis, renal tubular disease

Question 21

RBC count

Answer 21

Normal range is decrease in adult females (blood loss during menstruation, but men have higher androgen levels that stimulate erythropoiesis)

Decreased in anemia (recommendations depend on types of anemia: iron deficiency, B12 deficiency, folic acid deficiency, hemolytic anemia, anemia of chronic disease, blood loss anemia)

Life span of 120 days

Question 22

RBC Indices

Answer 22

tests that further describe RBCs

MCV – mean corpuscular volume – average volume; how large the blood cells are (macrocytic or microcytic anemia)

MCH – mean corpuscular hemoglobin- (amount of hemoglobin in the RBC- average)

MCHC – mean corpuscular hemoglobin concentration (amount of hemoglobin in the RBC as function of hematocrit- %volume)

Question 23

RDW

and

Reticulocyte

Answer 23

RDW - RBC distribution width – indicates variation in size of RBC

Reticulocyte (immature RBC) count – indirect assessment of new RBC- precede mature RBC by 1-2days before they mature):

II. elevation occurs in acute blood loss b/c bone marrow trying to replenish RBC lost in the periphery)

Question 24

ESR

Causes and Symptoms

Low and High

Answer 24

RBC usually settles slowly in plasma but will settle faster when there are changes in the electrostatic forces

ESR – erythrocyte sedimentation rate- rate RBC settles

• High

Causes: Pregnancy, Rheumatoid arthritis, Infection

Symptoms: Limited to associated disorder

• Low

Causes: Heart failure, High dose steroids, Liver disease

Symptoms: Limited to associated disorder

Question 25

Hgb

Answer 25

–major content of RBC; carries O2 from lungs to the rest of body where it is then burned to create energy II. - direct indication of oxygen-transport capacity of the blood III. low in anemia (fatigue)

Question 26

Hct

Answer 26

- percentage of blood composed of erythrocytes; - Usually 3x the value of Hgb - Decreased in anemia

Question 27

WBC

Answer 27

- leukocytes (lymphocytes and granulocytes (which come from hematopoiesis) High: Causes: High Infection Symptoms: Fever, chills Low Causes: Immune suppression Symptoms: Limited to underlying disorder

Question 28

Differential (CBC with Dif)

Answer 28

Left Shift – absolute increase in number of bands Indicates an acute infection

Question 29

Absolute Neutrophil Count (ANC)

Answer 29

ANC = [(WBC)(%PMN + %Bands)]/100% ANC \< 1500 indicates neutropenia (indicates risk of infection) Caused by drugs (chemo) and by some diseases (HIV)

Question 30

Diagnosing or predicting risk of thrombosis

Answer 30

**d-dimer** - Primarily used to diagnose disseminated intravascular coagulation (DIC) - Needs further study for other disorders

Question 31

Monitoring anticoagulants

Answer 31

Normal INR in a non-anticoagulated patient: 1.0 Target INR/range for MOST indications: 2.5 (2-3) Target INR for mitral valve replacement (MVR): 3 (2.5-3.5)

Question 32

aPTT

Answer 32

Target aPTT: 1.5 to 2.5 times the control

Question 33

Synthetic liver function Albumin

Answer 33

Question 34

Pre-albumin

Answer 34

- Shorter half-life (2 days) - Smaller volume of distribution - More sensitive to protein nutrition - Less sensitive of liver disease and hydration - Best test for assessing nutritional status (i.e. patients receiving TPN)

Question 35

PT/INR

Answer 35

Total bilirubin = insoluble + soluble = unconjugated + conjugated = indirect + direct

Question 36

Hepatocellular liver injury

Answer 36

False-positives: uremia, hemolysis, vigorous exercise ## Footnote Medications: Rx, OTC, herbal STATINS Unexplained: will usually return to normal

Question 37

Inflammation of liver

Answer 37

- Specific histologic pattern in hepatocyte - Multiple cause: o Viral: Hep A, B, C, D, E, G o Medication: majority are minor, transient, asymptomatic o Fatty liver

Question 38

Putting it all together (NEED TO KNOW)

Answer 38

AST/ALT \>1000 International units/mL: acute viral hepatitis, severe drug/toxin reactions, AST/ALT = 2 & GGT elevated: alcoholic hepatitis Isolated increase in AST: cardiac or muscle damage Elevated AST/ALT & elevated creatine kinase: muscle damage

Question 39

Pancreatic function

Answer 39

\>3-5 x ULN

Question 40

Urinalysis Macroscopic

Answer 40

Question 41

Urinalysis Microscopic Cells

Answer 41

Casts – gives information about where the damage occurred

Question 42

Urinalysis Microscopic Crystals

Answer 42

- Composed of uric acid, calcium phosphate, calcium oxalate, cystine - Drug-induced: indinavir, sulfamethaxazole, ciprofloxacin