Complete Chemistry Profile Glucose Formed from carbohydrate digestion and conversion of glycogen to glucose by the liver. Regulated by glucagon and insulin. Glucagon accelerates glycogen breakdown in the liver and increases blood glucose level. Insulin increases cell membrane permeability to glucose, and transports glucose into cells. Glucose Insulin binds to insulin receptors on the surface of target cells found in fat and muscle. Opens channels so that glucose can pass into cells where it can be converted to energy. ACTH, adrenocorticosteroids, epinephrine, and thyroxine play key roles in glucose metabolism. Glucose Hyperglycemia Diabetes Drugs: Steroids, epinephrine, amphetamines, thiazides Critical illness Hypoglycemia Reactive postpandrial, or fasting Insulin mediated or insulinoma Pseudohypoglycemia (Laboratory) Factitious (Non therapeutic adm of sulfonylureas or insulin) Sodium Cation 90% of the electrolyte fluid. Chief base of the blood. Chemically maintains osmotic pressure and acid base balance to transmit nerve impulses. Mechanisms to maintain Na+ levels in plasma and extracellular fluid include renal blood flow, carbonic anhydrase enzyme activity, aldosterone, renin enzyme secretion, ADH, and vasopressin secretion. Potassium Principle cation of intracellular fluid. Primary buffer within the cell. 90% concentrated within the cell, when damaged cells release K+ into the blood. 80-90% excreted in the urine by the glomeruli. Kidneys do not conserve K+. Average daily consumption is 80-200 mEq/day. Potassium Facilitates nerve conduction, muscle function, acid base balance, and osmotic pressure. Controls rate and force of contraction of the heart, CO. K+ and Na+ ions are important in renal regulation of acid base balance as hydrogen ions are substituted for Na+ and K+ions in the renal tubule. Potassium K+ Deficiency causes intracellular increase bicarbonate causing the pH to be alkaline. The respiratory center responds by increasing PC02 through hypoventilation. K+ concentration is affected by adrenal hormones. K+ deficiency causes a significant reduction in protein synthesis. Hyperkalemia Increase K intake (Diet, Blood transfusion, TPN) K movement out of the cell (b blocker, Rjabdomyolysis, Burns, Tumor lysis syndrome, metabolic acidosis Decrease k excretion (ACEI, K sparing diuretics, NSAIDs Hypoaldosteronism Renal insufficiency Hypokalemia GI loss Intracellular shift (albuterol, excessive beta stimulation, hyperthyroidism, insulin) Renal losses (diuretics, adrenal steroid excess) Chloride Anion that exists in the extracellular spaces. Maintains cellular integrity through osmotic pressure, acid base and water balance Excreted with cations during massive diuresis. Diagnoses disorders of acid base and water balance. CO2 Lower-than-normal levels Addison disease Diarrhea Ethylene glycol poisoning Ketoacidosis Kidney disease Lactic acidosis Metabolic acidosis Methanol poisoning Salicylate toxicity (such as aspirin overdose) Higher-than-normal levels Breathing disorders Cushing syndrome Hyperaldosteronism Vomiting The following conditions may also alter bicarbonate levels: Alkalosis Delirium Dementia Renal tubular acidosis; distal Renal tubular acidosis; proximal Calcium Bulk of Ca+ stored in the skeleton and teeth 98-99% 50% of blood calcium is ionized 50% is protein bound Only ionized calcium can be used by the body for muscular contraction, cardiac function, transmission of nerve impulses and blood clotting. Test measures concentration of total and ionized calcium in blood and reflects parathyroid function, calcium metabolism and malignancy activity. Phosphate 85% is combined with calcium in the bone 15% remains within the cells Required for generation of bony tissue and functions in the metabolism of glucose and lipids, the maintenance of acid base balance and the transfer of energy from one site in the body to another. Phosphate Phosphorus enters the RBC with glucose. Levels are evaluated in relation to CA+ levels. There is an inverse relationship. Decreased phosphorus may be due to elevated calcium levels. Controlling factor is PTH Magnesium Concentrated in the bone, cartilage and within the cell. Required for the use of adenosine triphosphate (ADP) Necessary for carbohydrate metabolism Protein synthesis Nucleic acid synthesis Contraction of muscular tissue Magnesium Regulates neuromuscular irritability and clotting mechanism. Importance in absorption of calcium from intestines. Deficiency results in Ca+ coming out of the bones and causing abnormal calcification in the aorta and kidney. 95% of magnesium is filtered through the glomerulus and reabsorbed in the tubule. Blood Urea Nitrogen Urea forms in the liver along with CO2, constitutes the final product of protein metabolism. Excreted urea is dependant on dietary protein intake, increased excretion in fever, diabetes and increased adrenal gland activity. Measures the nitrogen portion of urea. Index of glomerular function in the production and excretion of urea. Increased BUN indicates protein catabolism, kidney impairment, severe impaired glomerular function. Creatinine Byproduct in the breakdown of muscle creatine phosphate as a result of energy metabolism. Removed from the body by the kidneys. Production of creatinine is constant as long as muscle mass remains constant. Decreased kidney function reduces excretion of creatinine. Diagnoses impaired renal function. BUN/Creatinine Increased blood urea nitrogen (BUN) may be due: prerenal causes (cardiac decompensation, water depletion due to decreased intake and excessive loss, increased protein catabolism, and high protein diet) renal causes (acute glomerulonephritis, chronic nephritis, polycystic kidney disease, nephrosclerosis, and tubular necrosis) postrenal causes (eg, all types of obstruction of the urinary tract, such as stones, enlarged prostate gland, tumors). Serum Osmolality Measure of number of dissolved solute particles in solution. Increases with dehydration. Decreases with fluid overload. Evaluates water and electrolyte balance. Assesses liver disease, ADH function, ethanol and ethylene glycol and methanol ingestions. Amylase & Lipase Amylase enzyme that changes starch to sugar. Produced in salivary glands, pancreas, liver, fallopian tubes. Lipase changes fats to fatty acids and glycerol. Pancreas is major source of lipase. Diagnose acute pancreatitis. Bilirubin Results from the breakdown of hemoglobin in RBCs and is a byproduct of hemolysis. Produced by reticuloendothelial system. Removed by the liver, excretes it into bile. Level is elevated when there is excessive destruction of RBCs or when the liver is unable to excrete bilirubin. Uric Acid Formed from the breakdown of nucleonic acids. End product of purine metabolism. Excreted by urine and stool. Overproduction occurs during excessive cell breakdown and catabolism of nucleonic acids. Used to evaluate renal failure, gout, and leukemia.