Glucose, magnesium, phosphate and proteins Flashcards
Glucose draw, range, location and general function
Glucose concentration in extracellular fluid is closely regulated so that a source of energy is readily available to tissues.
Draw tube: SST (as part of chem -7 panel), PPT, gray (if drawing only glucose)
Normal range: 60–110 mg/dL
Panic values: < 40 or > 500 mg/dL
Conditions and drugs causing Hyperglycemia
Diabetes mellitus, Cushing syndrome (10–15%), chronic pancreatitis (30%)
corticosteroids,phenytoin, estrogen, thiazides
Conditions and drugs causing Hypoglycemia
Hypoglycemia seen with insulinoma, adrenocortical insufficiency, hypopituitarism, diffuse liver disease, enzyme deficiency diseases (eg, galactosemia).
Drugs:insulin, ethanol,propranolol; sulfonylureas,tolbutamide, and other oral hypoglycemic agents.
DIABETES MELLITUS Diagnosis components
Diagnosis of diabetes mellitus requires:
A fasting plasma glucose of > 126 mg/dL on two or more occasions
Spot plasma glucose level ≥200 mg/dL
HbA1c≥ 6.5% along with symptoms of diabetes.
Patients with fasting blood glucose levels 110 mg/dL to 126 mg/dL are considered to have impaired fasting glucose.
Glycosylated hemoglobin levels (HbA1c ) are favored to monitor glycemic control in patients with diabetes mellitus.
Calcium function skeletally
CA PROVIDES STRENGTH & STABILITY FOR THE COLLAGEN & GROUND SUBSTANCES THAT FORMS THE STRUCTURAL MATRIX OF THE SKELETAL SYSTEM & IS A HUGE RESERVOIR FOR MAINTAINING BLOOD LEVELS OF CALCIUM
Bulk of Ca++ is stored in the skeleton
Anion Calcium integration
ANIONS (BICARBONATE, LACTATE, & CITRATE)
CA USED IN MUSCULAR CONTRACTIONS, CARDIAC FUNCTION, TRANSMISSION OF NERVE IMPULSES, & BLOOD CLOTTING
Albumin influence on calcium
DECREASES OR INCREASES IN ALBUMIN WILL AFFECT THE TOTAL CALCIUM LEVEL, BUT WILL NOT AFFECT THE IONIZED PORTION
Amount of protein in blood will affect Ca++ levels
Muscular system, cardiac, nervous and heme calcium roles
CA USED IN MUSCULAR CONTRACTIONS, CARDIAC FUNCTION, TRANSMISSION OF NERVE IMPULSES, & BLOOD CLOTTING
Total Ca++ is made up of 3 fractions
Protein bound (∼40%)
Anion bound (∼10%)
Ionized “free” (∼50%) (metabolically active)
Only the ionized Ca++ can be used by the body for vital cellular processes
Calcium regulation
controlled by PTH, calcitonin, vitamin D & renal reabsorption
Ionized calcium functions
Participates in enzyme reactions
Important intracellular second messenger for “amplification”
Contributes to membrane potentials & neuronal excitability
Exocytosis of neurotransmitters at NMJ & CNS
Muscle contraction (skeletal, smooth, cardiac)
Participates in hormone release
Influences cardiac automaticity
Required for coagulation in intrinsic pathway
SERUM CALCIUM uses
Evaluating pts with known or suspected hyper/hypocalcemia
Evaluating electrolyte status in pts receiving IV fluids
Procedure:
Obtain 5ml of venous blood collected in red, yellow or speckled top tube
Reference range:
Varies considerably throughout adolescent years
Normal adult values: 8.9-10.1 mg/dl
Interfering factor in calcium
Thiazide diuretics
Large amount of blood transfusions
Pts undergoing dialysis
Excessive laxative use
Acid base disorders
Increased or decreased protein levels
Calcium levels are inversely related to phosphate levels
HYPERCALCEMIA
total Ca++ >12 mg/dl
Etiology:
Hyperparathyroidism
Malignancy (PTHrP producing tumors)
Granulomatous diseases
Thyrotoxicosis
Paget’s disease of bone
Bone fractures
Prolonged immobilization
Excessive intake of vitamin D
Clinical Manifestations of Hypercalcemia
Increased thirst
Polyuria, flank pain, signs of kidney stones or renal insufficiency
Anorexia, nausea, vomiting, constipation
Muscle weakness, atrophy, ataxia & loss of muscle tone
Lethargy, personality/behavioral changes, stupor or possible coma
HTN, shortening of QT interval & possible AV block
HYPOCALCEMIA
total Ca++ <8.5 but true hypocalcemia is ionized Ca++ <4.0 mg/dl
Etiology:
Pseudohypocalcemia
0.8 (nl alb - measured alb) + reported Ca
Hypoparathyroidism
Hyperphosphatemia
Malabsorption syndromes & malnutrition
Pancreatitis
Alkalosis
Vit D deficiency (rickets or osteomalacia)
Alcoholism & cirrhosis
Clinical Manifestations of Hypocalcemia
Paresthesias
Skeletal muscle cramps, abdominal spasms & cramps
Hyperactive reflexes, + Chvostek’s & Trousseau’s signs, tetany & laryngeal spasm
Hypotension, cardiac insufficiency, no response to drugs with Ca-mediated mechanism
Osteomalacia, bone pain, deformities & fractures
IONIZED CALCIUM uses and procedure
Particularly helpful during any surgical procedure that requires rapid & multiple whole blood transfusions
Second order test in the evaluation of pts with abnormal Ca++ levels
Neonatal calcium measurement
Assessing Ca++ levels in critically ill pts
Procedure:
5ml of venous blood in red, yellow, or speckled top tube
IONIZED CALCIUM LEVEL
Reference range:
Normal: 4.75-5.20 mg/dl
Panic values: <2.0 mg/dl may produce tetany or life-threatening complications, levels >7.0 mg/dl may cause coma
Increased levels:
Hyperparathyroidism
Ectopic PTHrP tumors
Increased vitamin D intake
Ionized calcium decreased levels and Interfering factors
Decreased levels:
Hypoparathyroidism
Vitamin D deficiency
Pts receiving bicarbonate to control metabolic acidosis
Acute pancreatitis
Hyperventilation to control increased ICP
Magnesium deficiency
Multiple organ failure
Interfering factors:
Improper specimen collection in EDTA
SERUM PHOSPHATE functions
85% of the body’s total phosphorus is combined with Ca+ inside bone; 14% resides within cells; 1% is the the extra-cellular compartment
Multiple functions – bones, glucose, lipids, acid-base balance, storage & energy transfer
Moves into cells after carbohydrate ingestion & therefore is lowered in the plasma
Inversely related to Ca++
SERUM PHOSPHATE functions 2
Major role in bone formation (bone matrix)
Essential for certain metabolic processes (ATP formation, building of enzymes for glucose, fat, & protein metabolism)
Cell structure (nucleic acids of DNA/RNA, membrane phospholipids
Serves as a acid-base buffer in the ECF & in the renal excretion of H+ ions
O2 delivery by RBCs through organic phosphates & 2,3 diphosphoglycerate
Serum phosphate uses
Evaluating pts with CKD or hyperparathyroidism
Evaluating alcoholic & malnourished pts or pts receiving TPN
Evaluating status of pts recovering from diabetic ketoacidosis or pts receiving IV fluids containing phosphorus
Evaluating pts with hyperparathyroidism
Procedure: same as other electrolytes
Reference range: 2.5-5.0 mg/dl
Interfering factors: hemolysis
HYPERPHOSPHATEMIA
Definition: >5 mg/dl
Etiology:
Decreased excretion due to renal failure
Hypoparathyroidism
Adrenal insufficiency & acromegaly
Increased intake & absorption
Redistribution/cellular release
Hypocalcemia
Bone tumors & cancer metastases
Clinical Manifestations of Hyperphosphatemia
Manifestations are usually related to the reciprocal changes that are seen in calcium (hypocalcemia)
Paresthesia’s, tetany, Chvostek’s and Trousseau’s signs
Hypotension and cardiac dysrhythmias
Skeletal muscle cramps, abdominal spasms & cramps
Bone pain
HYPOPHOSPHATEMIA
Definition: <2.5 mg/dl
Etiology:
Hyperparathyroidism
Diabetic ketoacidosis
Antacids
Severe diarrhea
Vitamin D deficiency
Alkalosis
Alcoholism, malnutrition, and TPN
Renal tubular absorption defects
Clinical Manifestations og Hypophosphatemia
Manifestations usually related to reciprocal calcium changes (hypercalcemia)
Ataxia, hyporeflexia, muscle weakness, joint & bone pain
Increased thirst, anorexia, N/V, & constipation
Lethargy, personality/behavioral changes, stupor or possible coma
POLYURIA, FLANK PAIN, SIGNS OF KIDNEY STONES OR RENAL INSUFFICIENCY
HTN, SHORTENING OF QT INTERVAL & POSSIBLE AV BLOCK
SERUM MAGNESIUM
50% in bone, 49% in body cells, & 1% is dispersed within the serum
Mg is required as a cofactor for the production of cellular energy and function of cellular messenger systems
Along with Na, K, & Ca ions, Mg also regulates neuromuscular irritability and the clotting mechanism
The secretion, synthesis, & action of PTH is influenced by Mg
Mg & Ca are intimately linked in their body functions
Serum Magnesium further functions
Cofactor for intracellular enzyme reactions (transfers phosphate groups)
Essential for all ATP reactions
Essential for every step related to replication & transcription of DNA & for translation of messenger RNA
Required for cellular energy metabolism, function of the Na+/K+/ATPase pump
Stabilizes membranes
Contributes to nerve conduction, ion transport, & calcium channel activity
Serum Magnesium uses, procedure and Interfering factors
Evaluating renal function & electrolyte status in hospitalized patients
Pts with hypocalcemia or hypokalemia not responding to electrolyte correction
Identification of malabsorption disorders
Monitoring tx of pre/eclampsia
Procedure: same as other electrolytes
Reference range: 1.5-3.0 mEq/L
Interfering factors:
Hemolysis, lithium or salicylates use
HYPERMAGNESEMIA
Definition: >3.0 mEq/L
Etiology:
Renal failure or dehydration
Treatment of pre/eclampsia
Rhabdomyolysis
Excessive use of antacids
Clinical manifestations of Hypermagnesmia
Lethargy, hyporeflexia, muscle weakness
Depressed respiration, apnea, confusion
HYPOMAGNESEMIA
Definition: <1.5 mEq/L
Etiology:
Alcoholism, malnutrition, malabsorption & starvation
Parenteral nutrition
Pancreatitis
Hypoparathyroidism
Clinical Manifestations of Hypomagnesmia
Personality changes, tetany, nystagmus, Chvostek’s & Trousseau’s sign, TACHYCARDIA, HYPERTENSION, and CARDIAC ARRHYTHMIAS
Altered PTH secretion/action may occur
SERUM PROTEINS functions
Source of nutrition
Buffer system
Immune function
Carrier proteins
Metabolic function
Chromosomal & DNA components
Cell membrane structure
colloidal osmotic pressure
Antiprotease
Serum Albumin
Part of a diverse microenvironment which primarily maintains colloidal osmotic pressure
Source of nutrition & also part of a complex buffer system. It is a “negative” acute phase reactant
Useful for:
Evaluation of nutritional status, albumin loss in acute illness
Evaluation of pts with liver or renal disease, hemorrhage, burns or leaks in GI tract
Serum Albumin
Reference range:
Normal: 3.5-4.8 g/dl
Increased levels:
Volume depletion or dehydration
Decreased levels:
Acute/chronic inflammation & infection
Cirrhosis, liver disease & alcoholism
Nephrotic syndrome
Crohn’s, colitis, malabsorption
Burns & severe skin disease
Procedure: same as electrolytes (red, yellow SST tube or plain red tube )
Serum Albumin interferring factors
Pregnancy
Oral contraceptives (OCP) & estrogen replacement
Prolonged bed rest
IV fluids, rapid hydration or overhydration
Is not a good indicator of recent changes in nutrition due to prolonged half-life in serum
SERUM PROTEIN ELECTROPHORESIS (SPEP)
Separates albumin & globulins with an electric field to differentiate the proteins according to size, shape & electric charge into 5 distinct fractions
[Albumin, alpha-1-globulin, alpha-2-globulin, beta-globulin, gamma-globulin]
Useful for:
Detection of monoclonal protein or monitoring size of monoclonal peak in multiple myeloma pts
SPEP Interpretation
↑ & ↓ albumin
↑ in total serum protein
Volume depletion or dehydration
Multiple myeloma
Sarcoidosis & other granulomatous diseases
Any inflammatory state
↓ in total serum protein
Poor nutritional status, liver disease, alcoholism, burns, severe skin disease
Renal disease, Crohn’s, UC
SPEP more interpretation
Increases in gamma-globulin protein
Multiple myeloma, leukemia & other cancers
Autoimmune disease, chronic infections
Decreases in gamma-globulin protein
Nephrotic syndrome
Hereditary aggamaglobulinemia
Increases in beta-globulin protein
Multiple myeloma, biliary cirrhosis, obstructive jaundice
Decreases in beta-globulin protein
Nephrosis
