Lab Values Part 2

Blood pH is regulated by which two organ systems?

Lungs and kidneys

What causes respiratory acidosis?

CO₂ retention (hypoventilation)

What causes respiratory alkalosis?

CO₂ loss (hyperventilation)

What primarily regulates bicarbonate levels?

Kidneys

What does PaCO₂ reflect?

Ventilation status

What does PaO₂ reflect?

Oxygenation

What is albumin's main function?

Maintains oncotic pressure

Where is albumin produced?

Liver

What causes low albumin levels?

Malnutrition or liver disease

What lab is most sensitive for short-term nutrition?

Prealbumin

What is the main role of globulins?

Immune function

What is uric acid a product of?

Nucleic acid metabolism

What causes increased uric acid levels?

↓ renal excretion or ↑ production

What does A1c measure?

Average glucose over ~3 months

Why does A1c reflect long-term glucose?

Based on RBC lifespan

Why is A1c more reliable than daily glucose checks?

Captures fluctuations over time

What is bilirubin derived from?

Hemoglobin breakdown

Where is bilirubin conjugated?

Liver

Which bilirubin is water-soluble?

Conjugated (direct)

What causes increased indirect bilirubin?

Hemolysis or impaired conjugation

What causes increased direct bilirubin?

Biliary obstruction

What type of jaundice is caused by RBC destruction?

Prehepatic

What type of jaundice is caused by liver dysfunction?

Hepatic

What type of jaundice is caused by bile duct obstruction?

Posthepatic

Which liver enzyme is more liver-specific?

ALT

Which liver enzyme can also rise in MI?

AST

What does a very high AST/ALT suggest?

Hepatocellular injury

What does elevated alkaline phosphatase indicate?

Cholestasis or bone disease

What does elevated GGT suggest?

Alcohol use or hepatobiliary disease

What is CK-MB specific for?

Cardiac muscle damage

What determines severity of MI with CK-MB?

Amount released correlates with damage

Which cardiac marker is most specific for MI?

Troponin

What does BNP indicate?

Heart failure

Why is BNP released?

Ventricular stretch/volume overload

What does TSH measure?

Pituitary stimulation of thyroid

What does high TSH indicate?

Hypothyroidism

Why is TSH elevated in hypothyroidism?

Lack of negative feedback

What does low TSH indicate?

Hyperthyroidism

What is ferritin a marker of?

Iron stores

What does low ferritin indicate?

Iron deficiency anemia

What does TIBC measure?

Available iron-binding capacity

Why is TIBC elevated in iron deficiency?

More binding sites available

What does serum iron measure?

Iron bound to transferrin

What does a CBC evaluate?

Blood cell components

What does hemoglobin reflect?

Oxygen-carrying capacity

What does hematocrit represent?

% of RBCs in blood

What does an increased reticulocyte count indicate?

Increased RBC production

What does MCV measure?

RBC size

What causes macrocytic anemia?

B12 or folate deficiency

What causes microcytic anemia?

Iron deficiency

What does ESR indicate?

Inflammation (nonspecific)

What is a "left shift"?

Increased immature neutrophils

Why does a left shift occur?

Bone marrow releases cells early

What are T cells responsible for?

Cell-mediated immunity

What are B cells responsible for?

Antibody production

What do monocytes become in tissues?

Macrophages

What are eosinophils associated with?

Allergic reactions

What are basophils associated with?

Myeloproliferative disorders

What can cause increased platelets?

Cancer, inflammation, iron deficiency

What can cause decreased platelets?

Drugs, hemorrhage, decreased production

What does aPTT evaluate?

Intrinsic clotting pathway

What medication is monitored with aPTT?

Heparin

What does PT evaluate?

Extrinsic pathway

What medication is monitored with PT/INR?

Warfarin

Why is INR used?

Standardizes PT across labs

What does urine specific gravity reflect?

Kidney concentrating ability

What does persistent protein in urine indicate?

Renal disease

What do WBCs in urine suggest?

UTI

What do casts in urine indicate?

Renal disease