"Must know" labs Flashcards
Calcium (Ca)
total: 8.5-10.5 mg/dL
ionized: 4.5-5.1 mg/dL
- calculate corrected Ca if albumin is low.
- correction is NOT needed for ionized
- incr w/ Ca supp, vit D, thiazide diuretics
- decr. w/ long-term heparin, loop diuretics, bisphosphonates, cinacalcet, systemic steroids, calcitonin, foscarnet, topiramate
- supplement Ca in pregnancy, osteoporosis
Magnesium (Mg)
1.3-2.1 mEq/L
- incr. w/ Mg-containing antacids & laxatives w/ renal impairment
- decr. w/ PPI, diuretics, amphotericin B, foscarnet, echinocandins, diarrhea, chronic alcohol intake
Phosphate (PO4)
2.3-4.7 mg/dL
- incr. w/ renal failure
- decr. w/ phosphate binders, foscarnet, PO Ca intake
Potassium (K)
3.5-5 mEq/L
- incr. w/ ACEi, ARBs, aldosterone receptor antagonists, aliskiren, canagliflozin, cyclosporine, tacrolium, mycophenalate, K supp, bactrim, drospirenone containing PO contraceptives, chronic heparin kus, NSAIDs, pentamidine
- decr. w/ beta-2 agonists, diuretics, insulin, steroids, conivaptan
Sodium (Na)
135-145 mEq/L
- incr. w/ hypertonic saline, tolvaptan, conivaptan
- decr. w/ carbamazepine, oxcarbazepine, SSRIs, diuretics, desmopressin
Bicarbonate (HCO3)
venous: 24-30 mEq/L
arterial: 22-26 mEq/L
- assess acid-base status
- incr. due to loop diuretics, systemic steroids
- decr. due to topiramate, zonisamide, salicylate overdose
Blood Urea Nitrogen (BUN)
7-20 mg/dL
- incr. w/ renal impairment and dehydration
- used w/ SCr to assess fluid status and renal funct.
Serum Creatinine (SCr)
0.6-1.3 mg/dL
- incr. w/ drugs that impair renal funct
- decr. w/ low muscle mass, amputation, hemodilution
- false incr. w. bactrim, H2RAs, cobicstat
Anion Gap
5-12 mEq/L
elevated = metabolic acidosis
White blood cells (WBC)
4K-11K cells/mm2
- used to diagnose & monitor infection/inflammation
- incr. as acute phase reactant, indicating a systemic reaction to inflammation or stress
neutrophils
45-73%
determine likelihood of infection and with acute WBC in absolute neutrophil count calculation
- neutrophils = SEGmented neutrophils (“segs”)
- immature neutrophils = bands
bands
3-5%
released from bone marrow to fight infection
eosinophils
0-5%
incr in drug allergy, asthma, inflammation, parasitic infection
basophils
0-1%
incr. in inflammation, hypersensitivity reaction, leukemia
lymphocytes
20-40%
incr. in viral infections, lymphoma
decr. in bone marrow suppression, HIV, or systemic steroids
Red Blood cells (RBC)
males: 4.5-5.5 x 10^6 cells/microL
females: 4.1-4.9 x 10^6
- incr. w/ erythropoiesis-stimulating agents (ESAs), smoking and polycythemia
- decr w/ chemo that targets bone marrow, low production, blood loss, deficiency anemias, hemolytic anemia, sickle cell anemia
hemoglobin (Hgb, Hb)
males: 13.5-18 g/dL
females: 12-16 g/dL
- Hgb carries O2 in RBCs
- incr. w ESAs
- decr. w anemias and bleed
Coombs Test and G6PD for drug-induced anemia
mean corpuscular volume (MCV)
80-100 fL
- incr. due to B12 or folate deficiency
- decr. due to Fe deficiency
folic acid (folate)
5-25 mcg/L
B12 and folate are ordered for further workup for macrocytic anemia
- decr. due to phenytoin/fosphenytoin, phenobarb, primidone, MTX, bactrim, sulfasalazine
supplement folate in women of childbearing age and alcoholism
Vitamin B12
> 200 pg/mL
decr. due to PPIs, metformin, colchicine, chloramphenicol
reticulocyte count
0.5-2.5%
measures reticulocytes being made in the bone marrow
- reticulocyte count incr. in blood loss and decr. in untreated anemia due to iron, folate or B12 deficiency & bone marrow suppression
Coombs Test, direct (DAT)
negative
diagnose hemolytic anemia, when the cause of hemolysis is unclear
- can be caused by penicillins/cephalosporins, dapsone, isoniazid, levodopa, methyldopa, methylene blue, nitrofurantoin, pegloticase, primaquine, quinidine, quinine, rasburicase, rifampin, sulfonamides
a (+) coombs test + likely drug cause: d/c drug
