Labs Flashcards
Generally, when should you order lab tests?
When it will possibly change the treatment or clinical outcome
(for a reason)
What 2 organ systems would it be considered “too late” when the physical exam reveals an abnormality?
Liver and Kidney
What time should you put on a lab order if you want the results right away?
STAT (always in ER/ICU)
What time should you put on a lab order if you want the results by next shift?
No time
What time should you put on a lab order if you want the results at a specific time?
State the exact time
True or False: when writing a lab order, “now” is mutually acceptable as “STAT”
False
“now” should never be written
Which lab consists of the following items?
WBC, RBC, Hb, Platelets, Differential on WBCs, Indices, and Hct
CBC
This is a listing of the absolute and the percentage of the specific types of WBCs
Differential
What 2 main reasons should you order a CBC?
Detecting Disease
Monitoring disease
What are the 6 WBC types that are found on the differential for a CBC?
Neutrophils
Lymphocytes
Monocytes
Eosinophils
Basophils
Bands (immature WBCs)
What are “segs”?
Neutrophils (their nucleus is segmented)
What is a “left shift”?
The trend towards less mature WBC’s or towards an increase in neutrophils.
What would infection, inflammation, anoxia, drugs, or stress/pain do to WBC production?
↑ production and release of immature cells
What are thee 6 etiologies for neutrophilia?
Metabolic disorders
Acute infection
Drugs/toxins
Hematological disorders
Acute inflammation
Tissue necrosis
(MAD HAT)
Viral infections, some bacterial infections, chronic inflammatory disorders, and blood diseases will raise which WBC?
Lymphocytes
Bacterial infections, viral infections, hematological disorders, and collagen vascular disease will raise which WBC?
Monocytes
Parasitic diseases, allergic disease, skin disorders, and malignancies will raise which WBC?
Eosinophils
Define the following acronyms:
MCHC MCV MCH RDW
MCHC- mean corpuscular hemoglobin concentration
MCV- mean corpuscular volume
MCH- mean corpuscular Hb
RDW- RBC distribution width
What are the 3 broad topics that describe a decrease in RBC count?
Microcytic hypochromic anemia
Normocytic normochromic anemia
Macrocytic anemia
What are the 2 broad topics that increase the RBC count?
Polycythemia vera (PV)
Secondary polycythemia
What will a B12 or folate deficiency do to MCV?
increase it
What are the 2 main conditions that cause a ↓ MCV?
Iron deficiency anemia
Hemolytic anemia
Infections or myeloproliferative disorders will cause what change in platelet count?
↑ platelets
What 2 general things can cause a decreased platelet count?
↓ production (marrow depression)
↑ destruction (autoimmune)
What will toxins and drugs do to reticulocyte count?
↓ reticulocytes
What 2 things will ↑ reticulocyte count?
Hemolytic anemia
Acute blood loss
What will anemia, blood loss, fluid retention, or edematous states (CHF) do to [Hb]?
↓ Hb
If a patient has blood loss, anemia, or state or hydration, what measurement can you use to evaluate it?
Hct
Generally, which lab test screens for Renal + Electrolytes?
BMP
What does a BUN:Cr > 20 indicate?
Prerenal azotemia
(Dehydration causes ↑ BUN reabsorption, which ↑ this ratio)
What does a BUN:Cr from 10-15 indicate?
Renal state
(normal)
What does a BUN:Cr <20 indicate?
Postrenal azotemia
(Obstruction ↓ BUN reabsorption, which ↓ this ratio)
What is the difference between azotemia and uremia?
Azotemia- ↑ BUN and Cr in blood (lab Dx)
Uremia- ↑ urine in blood, refers to end-stage kidney disease/renal failure.
(all uremic pts are azotemic, but not all azotemic pts are uremic)
What is the formula to determine creatinine clearance when only the serum creatinine is known? Males and Females
Male: (Kg)*(140-age)/72*(serum Cr)
Female: (Kg)*(140-age)*(0.85)/72*(serum Cr)
What is the main reason to order a serum Cr level?
Assess GFR (renal fxn)
What is a common cause of hypercalcemia based on elevated PTH?
Primary hyperparathyroidism with an adenoma
What is the most common cause of hypocalcemia?
Hypoalbuminemia
What is the eqn to adjust serum Ca under a depressed albumin?
Adjusted Ca = (serum Ca) - (serum albumin) + 4.0
What metabolic state causes decreased CO2?
Metabolic acidosis
Respiratory alkalosis, renal disease (pyelonephritis), severe dehydration, and DI can cause an increase in which ion?
Cl-
What 3 things can cause a loss of Cl-?
Renal loss (loop diuretics)
GI loss
Metabolic alkalosis (vomiting HCl)
Diabetes, Acute pancreatitis, endocrine dysfxn, and drugs can cause what change in [glucose] in the blood?
Hyperglycemia
What mg/dl of fasting blood sugar do you need to be diagnosed with diabetes mellitus?
> 126 mg/dl
What mg/dl of random blood sugar do you need to be diagnosed with diabetes mellitus?
> 200 mg/dl