Lecture 5- BMP and CMP

what is included in a BMP

• kidney function:

  • BUN

  • creatinine

  • eGFR calc

• endocrine

  • glucose

• electrolytes:

  • calcium

  • sodium

  • potssium

  • chloride

• blood gas/pH

  • CO2 (bicarb)

checking volume, acid/base, CHF, and kidney failure

components of CMP

all of BMP +

• albumin

• alkaline phosphate

• alanine aminotransferaase

• aspartate aminotransferase

• bilirubin

checiing liver funvton adn nutritional status

when to order BMP vs CMP

BMP

• routine screening

• monitor electrolytes

• renal function

• acid base stsus

• glucose

• common in: ED, preop, medication monitoring (diuretics, ACE inhi, ARBs)

CMP

• hepatic func also neeeded

• common in : annual wellness exam, sus liver diseasem mutritional assessment

creatinine (Cr)

• only excreted by kidney

• produced by skeletal muscles as part o fmetabolic preocesses

• released into circualtion at constant rate

• freeely filtered acrss glomerulus

  • no reabsorbed by tubules→ secreted in minimal amnts

• decreased filtration bu kidneys → ioncreased serum lvels

• can be impacte dby muscle mass:

  • lw ,uscle mass an cause artificially low level → over estimating GFR and renal fucntion

  • high muscle mass can cause higher levels of creatinine → under estimarte GFR and renal function

acute kidney injury and Cr

• increased serum Cr by 0.3mg/dL or 50% in 48 hrs → AKIN

factors that control for creatinine testing

• age

• ethnicity

• gender

blood urea nitrogen (BUN)

• reflects urea prod (liver) adn resabsoprtion/secretion (nephron)

• azotemia= increase in BUN

  • more nitrous waste in blood than usual

• dietary protein intake, muscle mass, asvanced preg

• elevated BUN→ upper got it! bleedm protein overloas, corticosteroids

BUN: Cr

• assess kidney ad nliver function

• increase ith age and wirh decreasing muscle mass

• ratio <20:1

  • prerenal causes- voluem depletion

• ratio 20:1

  • intrinsic renal causes (glomeruloenohritis, CKD)

eGFR

• assess kidney fiunction

• calculated with CKD-EPI equation

glucose

• assess blood glucose lvels; eval for diabetes

• critical values: <50 and >450mg/dL (male); <40 and >450 (female)

sodium (Na+)

• critical values <120 or >160mEq/L

• assess fluid and electroplyte balance

• primary extracellular cation

• determine dby dietary AN uptake and renal excretion

  • fluid/voluem stasis

• serum osmolality: measur o focnc of solutes in blood serum

hyponaturemia

low levels of Na+

• impact both brain asndn nervous ystem

• timing: acute (48 hours) vs chronic > 48 hours

sx hyponaturemia

• weakness

• headache

• conusionm delerium

• lethargy

• stupor

• coma

hyponaturemia- hypovolemic

• diuretics

• GI loss (vomit, diarrhea)

hyponaturemia- euvolemic

• SIADH

  • med, pain, psychosism surgery

hyponaturemia- hypervolemic

• HF

• cirrhosis

• nephrotic syndrome

• CKD

• acute kidney injury

hypernatremia

• incrased morbidity and mortality

  • mvmt of water in adn out of cell→ demyelination

sx hypernatremia

• orthostatis HTN

• tachycardia

• dry mucu smembranes

• fagtigue, lethary

• non speciifc weakness

• seizures

• coma

associations hypernatremia

• increase Na intake

  • dietary, IV fluids

• decraease Na loss

  • cushing syndrome - aldosterone like effect (increase serum Na)

  • hyperaldosteronism

• increase free body water loss→ increase Na

  • GI loss

  • excesive sweating

  • diabetes insipidus - ADH deficiency

  • sectensive burns

  • osmostic iduesis

• decreased fre body water loss

  • restrained

  • sedated

  • intubated

• med:

  • steroids

  • estrogens and OCP

  • laxatives

common causes of hypernatremia and hyponatremia

calcium (Ca)

• use: neuromuscular disease, cardiac function, bone metabolism, eval PT function, renal diseases and some malignances

• correct for hypoalbuminemia, pH status, prolonged torniquet time

hypercalcemia

• hyperparathyroidism

• malignancy

• excessive vit D intake

• thiazide diuretics

hypocalcemia

• hypoparathyroidism

• low vit D

• renal failure

• Mg deficiency

• massive transfussion

potassium (K)

• critical values: <3 or >6.1 mmol/L

• important in caridiac function; maintenance of memebrane elcetrical potential (neuromuscular tissue) affecting heart rate and contractility

• most abundant intracellular cation

• excreted by kidneys with NO renal resorption

  • levels can drop if not adequte in diet or IV infusion

common factors affecting K

• meds

• dietary intake

• renal dysfunction→ acid-base balance - alkalotic states lower serum K, acidotic states INCREASE serum K

hypokalemia

• low levels <3.5 mEq/L

• decrease contractility

  • ascending muscel weakness

  • paralysis

  • cardiac arrhythmias excentuated

  • ECG changes

causes of hypokalemia

• decrease K intake

  • dietary and IV

• insulin admin- pushes K and glucose into cel

• diuretics→ need K supplementation

• burns

• GI

• hyperaldoseteronism

• sudhings

• renal tuubular acidosis

• renal artery stenosis

• acites

• alkalosis

• ensure Mg is good→ or else wasting us eof K bd Mg in charge of K regrulation

hyperkalemia

• high levels >5.5

• symptoms:

  • irritability

  • nausea/vomiting

  • GI cramping/colic

  • diarrhea

• signs:

  • ascending muscel weakness

  • paralysis

  • cardiac arrhythmias

  • ECG→ peaked T waves, widened QRS, depressed ST

hyperkalemia causees

• increase K intake

  • dietary, IV

• acute/chronic renal failure- inability of kidneys to excrete K

• addisons disease

• hypoaldosertonism

• acidosis (diabetic ketoacidosis)

• crush injury

• dehydration

• medications:

  • beta blockers

  • ACE inhibitors

  • aldosterone inhibiting diuretics

Chloride (Cl)

• use: electrolyte, extra cellular anion

• functions:

  • maintain electrical neutrality as salt with Na

  • affects water balance- water moves with sodium and chloride

  • buffer in acid-base - CO 2 cation increasem bicarb (anion) moves from intracellular space to extracellular space, Cl- will move back into cell to maintain electrical neutrality

carbon dioxide (CO2)

• assess serum pH and electrolytes

• major role in acid-base balance

• CO2 on BMP actually measures total carbon dioxide in venous blood, which is predoinately composed of bicarb (HCO3-)

• BMP CO2= serum bicarb

• ABG PaCo- dissolved CO2 gas

  • respiratory component

Cl and CO2 relationship

• inversely related

• Cl often moves inversely with bicarb

• CO2 reflects bicarb (main buffer against acid)

confounding factors : pseudohyperkalemia

• hemolysis (hemolyze as drawn)

• erythrocytosis (extrme)

• thrombocytosis (K released from platelets durign clotting)

  • prolonged tourniquet time

  • fist clenching during blood drawn

confounding factors : pseudohyponaturemia

• flasely low Na due to elevated lipids or proteins in serum

• check serum osmolarity- its normal

confounding factors: psuedohypocalcemia

• hypoalbuminemia- Ca is bound to albumin in serum

• MUST calculate correct Ca

• corrected Ca= measured Ca+ 0.8 x (4.0- albumin)

confounding factors

• acid-base status affects

  • acidosis shifts K extracellualry (increase serum K)

  • alkalosis shifts K+ intracellulary (decrease serum K)

• specimen handling:

  • delayed processing, pneumatic tube transport, adn temp extreme acan cause hemolysis→ false increase K

• BUN elevation w/o renal dz

  • upper GI bleed, high protein diet, corticosteroids, catabolic states

• Cr limitations:

  • affected by muscle mass (m=low in elderly→ overestimate GFR)

• IV fluid contamination:

  • drawing bloof from lien running IV fluids can dilute or concentrate electrolytes