Week 3 Interpreting Common Lab Values

Question 1

What are the common laboratory values that are taken?

Answer 1

• Complete blood count
• Urinalysis
• Clinical Chemistry Panels
• Hydration status

Question 2

Labs from CBC

Answer 2

• Hemoglobin (120-160 g/L)
• Red blood cells (RBC) (3.8-5.2x 10^12/L)
• Hematocrit (HCT): (0.36-0.46 L/L)
• Mean cell volume (MCV): (78-100 fL)
• Mean cell hemoglobin concentration (MCHC): (310-360 g/L)
• RDW: Red blood cell distribution width (<15.6%)
• White blood cell count (WBC) :4.5-13.5 x10^9/L.
• Platlets: (140-450 x10^9/L)

Question 3

normal range for hemoglobin

Answer 3

120-160 g/L

Question 4

normal range for RBCs

Answer 4

3.8-5.2x 10^12/L

Question 5

normal range for HCT

Answer 5

0.36-0.46 L/L

Question 6

normal range for MCV

Answer 6

78-100 fL

Question 7

normal range for MCHC

Answer 7

310-360 g/L

Question 8

normal range for RDW

Answer 8

<15.6%

Question 9

normal range for WBC

Answer 9

4.5-13.5 x10^9/L.

Question 10

normal range for platelets

Answer 10

140-450 x10^9/L

Question 11

What CBC blood values are important for IDA?

Answer 11

• ↓ hemoglobin: <12 g/dL (120 g/L)
• ↓ hematocrit (hypochromic): <0.35 L/L
• ↓ MCV (microcytic): <80 fL

Various combinations; depending on severity of depletion

Question 12

When might MCV be high

Answer 12

magoloblastic anemia
* B12/ folate issue

Question 13

What are the white blood cells with differentials?

Answer 13

granulocytes
* neutrophils
* % eosinophils
* % basophiles

non-granulocytes
* lymphocytes
* monocytes

Question 14

When might WBCs be increased/ decreased?

Answer 14

• ↑ with infections ,inflammation, cancers, leukemias
• ↓ with some autoimmune conditions, bone marrow suppression, and some medications like methotrexate

Question 15

Importance of urinalysis in screening

Answer 15

• To rule out a variety of disorders: infection, diabetes mellitus, renal disease, inborn errors of metabolism etc. Includes testing for presence of glucose, protein, RBC, bacteria etc.
• To assess over all hydration: urine specific gravity, pH important
• Can be prognostic for liver diseases when find high levels of bilirubin in urine

Question 16

What is assessed in the urinalysis?

Answer 16

Question 17

How doe specific gravity in the urinalysis change with dehydration?

Answer 17

dehydration = higher
* means higher concentration

Question 18

What values are assessed in the blood chemistry?

Answer 18

• Electrolytes: Na+, K+, Cl-, HCO3 or total CO2
• Glucose
• Creatinine, Urea (BUN)
• Will often include: AST/ALT, total bilirubin, calcium, phosphorus, magnesium
• May include: cholesterol, TG and CRP

Question 19

What are the conditions of low/ high sodium?

Answer 19

• hyponatremia (<130 mmol/L)
• hypernatremia (>145 mmol/L)

Question 20

Describe hyponatremia

Answer 20

<130 mmol/L
* Can be due to ↑ sodium losses (renal, GI etc), fluid overload/retention (due to liver diseases),
* chronically low sodium intake (IV administration) and/or excessive fluid administration
* diuretic therapy that causes sodium wasting,
* excessive ADH secretion (common in head trauma) leading to fluid retention
* CF sweat a lot and so lose excessive sodium (diagnostic criteria)

Question 21

Describe hypernatremia

Answer 21

> 145 mmol/L
* Most typically occurs in dehydration; rarely in excessive intake (possible via IV administration).
* Other diseases: Cushing Syndrome or Diabetes Insipidus (affects cortisol and adrenal gland function)

Question 22

What are the conditions of low/high potassium?

Answer 22

• Hypokalemia (< 3.5 mmol/L)
• Hyperkalemia (> 5mmol/L)

Question 23

Describe hypokalemia

Answer 23

< 3.5 mmol/L
* ↑renal losses (diuresis)
* ↑GI losses (diarrhea, vomiting, fistula)
* K+ wasting meds (thiazide and loop diuretics, etc)
* Shift into cells (anabolism, refeeding syndrome, correction of glucosuria or diabetic ketoacidosis)
* Inadequate intake

Question 24

Describe hyperkalemia

Answer 24

> 5mmol/L (worried at 6 mmol/L)
* Decreased renal excretion as in acute or chronic renal failure
* Medications, e.g. potassium sparing diuretics, beta blockers, ACE inhibitors
* Shift out of cells (acidosis, tissue necrosis, GI hemorrhage, hemolysis)

Question 25

Describe urea

Answer 25

Reflective of hydrational status, renal function and recent protein intakes * Typically elevated in renal disease (creatinine would also be elevated as well) or in dehydration * May be high if fed lots of protein intake; may be low with chronically low intakes of protein

Question 26

Describe creatinine

Answer 26

High levels reflective of renal damage, recent skeletal protein breakdown (not chronic where levels would be low).

Question 27

normal values for urea and creatinine

Answer 27

* urea: 3.7 mmol/L * creatinine: 40-110 mmol/L

Question 28

low versus high hydration status

Answer 28

* **Dehydration:** a state of negative fluid balance caused by decreased intake, increased losses, or fluid shifts * **Overhydration or edema**: increase in extracellular fluid volume; fluid shifts from extracellular compartment to interstitial tissues

Question 29

Symptoms of dehydration

Answer 29

* dry skin and mucous membrane, poor skin turgor, sunken eyeballs * orthostatic hypotension, central venous and pulmonary pressures all ↓ * ↑HR/ ↓Cardiac output * rapid weight loss (may be several kg) * ↓ urinary output/ ↑ urine specific gravity * elevated serum osmolality; ↑serum sodium, ↑urea * cool & clammy

Question 30

Clinical conditions where dehydration may occur

Answer 30

* rapid blood loss with trauma * high output fistulas in GI in short bowel patients

Question 31

treatment for dehydration

Answer 31

Fluid resuscitation: with fluids of similar concentration to restore blood volume/blood pressure * Usually isotonic fluid like normal saline or lactated Ringer’s solution given IV * consider electrolyte status (Na+, K+, Cl- ) in choice of solution. * TPN or enteral nutrition is NEVER USED to TREAT!

Question 32

What can lead to overhydration or edema?

Answer 32

* Caused by increase in capillary hydrostatic pressure or permeability * Decrease in colloid osmotic pressure * Physical inactivity (need PA to help push fluid in the venous system)

Question 33

fluid retention versus excessive intake with overhydration

Answer 33

Results from retention or excessive intake of fluid or sodium or shift in fluid from interstitial space into the intravascular space * **Fluid retention**: renal failure, CHF, cirrhosis of the liver, corticosteroid therapy, hyperaldosteronism * **Excessive intake:** IV replacement tx using normal saline or Lactated Ringer’s, blood or plasma replacement, excessive salt intake (big issue in renal or liver disease)

Question 34

Symptoms of overhydration

Answer 34

* Generalized edema/Pitting edema: leaves depression in skin when touched * Rapid weight gain (> 2-3 kg in short period of time) * Pulmonary edema: crackles on auscultation * Patient SOB with tachypnea, systemic BP may rise and then fall with cardiac failure. * Labs: low hematocrit, normal serum sodium, lower K+ and BUN (or if high, may mean renal failure)

Question 35

What does ND set with overhydration?

Answer 35

MD will set very tight TFI (may be 80 or 90% maintenance or lower)

Question 36

Sodium lab value changes with hydration status

Answer 36

* hypovolemia: typically ↑ but can be normal or ↓ * hypervolemia: ↓ * other factors influencing result: Serum sodium generally reflects hydrational status; not sodium balance or overall status (need urine collections for this).

Question 37

urine sp. gravity changes with hydration status

Answer 37

normal: 1.010-1.025 * hypovolemia: ↑ * hypervolemia: ↓

Question 38

urine osmolality changes with hydration status

Answer 38

normal: 200-1200 mosm/kg * hypovolemia: ↑ * hypervolemia: ↓ other factors influencing result: * Low: diuresis, hyponatremia, sickle cell anemia; * High: SIADH, azotemia,

Question 39

BUN changes with hydration status

Answer 39

normal: 3-7 mmol/L * hypovolemia: ↑ * hypervolemia: ↓ other factors influencing result: * Low: inadequate dietary protein, severe liver failure * High: pre-renal failure; excessive protein intake, GI bleeding, catabolic state, glucocorticoid therapy * creatinine may also rise in severe hypovolemia (but not good marker)

Question 40

serum albumin changes with hydration status

Answer 40

normal: * hypovolemia: ↑ * hypervolemia: ↓ other factors influencing result: * Low: malnutrition; acute phase response, liver failure * High: rare except in hemoconcentration

Question 41

HCT changes with hydration status

Answer 41

normal: M-42-52%; F-37-47% * hypovolemia: ↑ * hypervolemia: ↓ other factors influencing result: * Low: anemia, hemorrhage with subsequent hemodilution (occurring after approximately 12 hours) * High: chronic hypoxia (chronic pulmonary disease, living at high altitude, heavy smoking, recent transfusion)