Interpretation of Labs Flashcards
What’s included in a CBC?
RBC, WBC, Hgb, Hct, Platelets
Neutrophil predominance
a bacterial, inflammatory, or neoplastic process
Lymphocyte predominance
viral (Mono), pertussis (bacteria), or lymphocytic leukemia
Basophilia
Allergies, hypothyroidism (which lab values correlate w/ this?), splenectomy, neoplasm (CML, polycythemia vera)
Eosinophilia
parasitic, allergies, GI, cutaneous
Neutropenia
overwhelming bacterial infection, AIDS, hypersplenism, anaphylactic shock, cachexia
Lymphopenia
immunodeficiencies, adrenocortical hormone excess or corticosteroid tx, impaired lymph drainage, chemo, lymphoma/carcinoma, HIV
If MCV is <80?
Microcytic anemia (iron deficiency or absorption issue, chronic disease, spherocytosis)
If MCV >100?
Macrocytic anemia (b12 or folate deficiency, or some anti-retrovirals)
What’s a BMP used for?
Monitor kidney function, electrolytes, acid-base and fluid balance
What can cause hypoglycemia?
Fasting, excess insulin or sulfonylurea effects, hepatic/adrenal/renal insufficiency, insulinomas
What constitutes a hyperglycemic lab value?
If a pt is >126 mg/dl on 2 SEPARATE visits or when they’re fasting or a single event of >200.
What is BUN important for?
Determining volume status, along w/ creatinine
When does BUN increase?
Pre-renal azotemia
Renal azotemia
Post-renal azotemia
What are the BUN/Cr ratios for the azotemias?
Pre-renal: BUN/Cr>10
Renal: BUN/Cr<10
Post-renal: Bun/Cr»10
What can cause pre-renal azotemia? Why?
Hypovolemia (dehydration, CHF, cirrhosis, GI bleed)
If you’re dehydrated, there is low flow. At low flow, the renal tubules increase reabsorption of urea relative to creatinine to increase osmolarity and retain more H2O.
What can cause renal azotemia?
Kidney isn’t excreting urea
What can cause post-renal azotemia?
Usually obstructive uropathy
When is BUN decreased?
Production of urea synthesis (liver disease or malnutrition)
Dilutional states (SIADH, 3rd tri. preg.)
What does creatinine measure?
Kidney function. Always take before contrast studies and to determine presence of renal injury (along w/ BUN)
When does creatinine secretion increase?
Increases w/ a decline in GFR. So, loss of renal fx= elevated creatinine
When might you get a false Cr increase?
With certain drugs. Salicylates, H2 blockers, fibrates.
What can cause increased renal loss?
hyperparathyroidism
renal tubular disease
chronic acidosis
What can cause cellular shift across bones?
acute respiratory alkalosis hyperalimentation TPN rapid tumor growth respiratory failure tx DKA
When is Na+ important to assess?
Neurological disorders, dehydration.
What does serum osmolarity measure?
Measures the bodys electrolyte-water balance. Is affected by changes in water content, temp, and pressure. It is the number of osmoles of solure/L of solution.
What does a high serum osmolarity indicate?
Indicates a greater concentration of solutes in the serum. AKA dehydration.
What’s the differency between osmolarity and osmolality?
Osmolarity (kg)
Osmolality (L)
What is the osmolar gap?
The difference between the measured osmolality and calculated osmolality.
What does it mean when you have an osmolar gap >10 mmol/L?
Indicates the presence of other osmotic reactive substances, like alcohol, methanol, mannitol, glucose.
What are the 3 types of hyponatremia and what conditions are present? Tx?
Hypovolemic hyponatremia (GI tract/renal losses –> judicious fluid replacement)
Euvolemic hyponatremia (SIADH –> restrict fluids
Hypervolemic (CHF, cirrhosis, CKI)
What is hypernatremia and what causes it?
Increase in sodium.
Caused by diarrhea, excess sweating, renal losses, DM, hypercalcemia, or hypOkalemia
why is K+ important?
Important in acid-base disorders that can cause electrolyte shifts
What can cause hyperkalemia?
Psuedohyperkalemia Reduced excretion Cellular shifts Meds decreasing RAAS K+ sparing diuretics NSAIDs
What can cause hypokalemia?
Poor diet GI and skin loss Renal loss Cellular shift Loop and thiazide diuretics Glucomineralcorticoids
Why is Cl- important?
Helps determine anion gap
What causes hyperchloremia
Non anion gap metabolic acidosis (diarrhea, RTA, lots of NaCl)
What causes hypochloremia
Prolonged vomiting Burns Diuretics Salt wasting Neuropathy Metabolic alkalosis
Why is CO2 important?
Important in determining presence and cause of metabolic acidosis
CO2 <22 –> metabolic acidosis
CO2 >29 –> metabolic alkalosis
What’s included on a CMP?
BMP + LFTs, Mg2+, PO4, Ca2+
Why is Ca2+ important?
Important in cardiac dysrhythmias and is often tied to other electrolyte abnormalities
What is hypocalcemia most often due to?
Hypoalbunimia and hypomagnesemia.
May also be caused by CKI, pancreatitis, pseudohypoparathyroidism.
Why is Mg2+ important?
Cardiac dysrhythmias and neuromuscular irritability
What medications may make you want to check a Mg?
Meds that can cause electrolyte abnormalities, such as diuretics and digitalis
What can cause hypermagnesemia
Excess intake in pt w/ CKI
Addisons
hypoT
lithium tox
What can cause hypomagnesemia
Malabsorption
Chronic diarrhea
Increased urinary loss
PO4 levels are important in…?
Renal insufficiency and any condition involving massive cell death (crush injury, hemolysis, tumor lysis, burns)
Which test is specific to liver?
ALT. AST also found in heart, blood, and skeletal muscle.
What values differentiate EtOH liver necrosis and chronic liver disease?
AST>ALT 2:1 = EtOH
ALT>AST = CLD
Where is alk phos found?
Liver, bone, intestine, placenta
Most common causes for indirect bilirubinemia?
Gilberts, hemolysis, recent hematoma, ineffective erythropoiesis
Most common causes for direct bilirubinemia?
stones, intrahepatic cholestasis, hepatitis, cirrhosis, toxins
When do lipase levels peak?
Lipase levels elevate 3-6 hours after acute onset pancreatitis and peak at 24 hours
If both amylase and lipase are high?
Renal failure
If only lipase is high?
Cholecystitis, perfd peptic ulcer
Of only amylase is high?
Intestinal perf Ischemia Obstruction DKA ruptured ectopic
When does trop I peak?
Released within hours of MI/ischemia. Can be detected 1-6 hours following CP onset. Peak at 12-16 hours and remain elevated for 5-9 days.
What else may cause elevated trop I?
Myocarditis Cardiac surgery Angina Unstable angina CHF Renal Failure PE
What does BNP help you differentiate?
It is released by atria due to stretch. Distinguishes between pulmonary and cardiac causes of dyspnea.
What does an elevated BNP mean and what can cause it?
BNP > 400 suggest heart failure.
MI, A-fib, Pulm HTN, CKI, sepsis, age
When to order a D-dimer?
RO PE or DVT. May get false + in inflammation, pregnancy, recent surgery
What indications would you order serum lactate in?
Hypoxia
Metabolic disorders
Toxins
What are reversal agents for coumadin tox. and heparin tox?
Coumadin: Vit. K
Heparin: Protamine sulfate
What indicates a UTI on a UA?
Nitrates, leukocyte esterase, WBCs, and bacteria
What are the 2 FOBT tests?
- Heme (cheap, fast)
2. Globin (expensive, more sensitive/specific, slow)
When might you get a false negative FOBT?
Proximal GI lesions (lacking oxidation of heme)
When might you get a false + of FOBT?
Myoglobin/Hb in red meat
Some veggies
High TSH and low free T4….
Hypothyroidism. Need to replace thyroxine.
What EtOH levels are considered evidence of impaired driving?
80 mg/dL or higher. Fatal if at 400.
Classic ASA toxicity presentation?
Mixed acid-base disturbance
Early respiratory alkalosis followed by elevated anion gap metabolic acidosis and possible late respiratory alkalosis
High sensitivity CRP is used to…?
Stratify cardiac risk
What causes a positive monospot test?
ebV. mono.
