L4: CHEMICAL EXAMINATION (GLUCOSE AND KETONES)

less than 70 mg/dL

• normal urine glucose

160-180 mg/dL

• renal threshold for glucose

fasting specimen

• recommended for screening

2-hours postprandial

• specimen useful for diabetes mellitus monitoring

first morning specimen

• specimen may not be fasting (residual glucose overnight)

glycosuria

• occurs when blood glucose is above renal threshold

diabetes mellitus

• most common cause of glycosuria due to hyperglycemia exceeding renal threshold

gestational diabetes

• hyperglycemia that occurs during and disappears after pregnancy

renal glycosuria

• disorders with increased anti-insulin hormones

• pancreatitis, acromegaly, cushing syndrome, hyperthyroidism, pheochromocytoma, thyrotoxicosis

• the hormones such as glucagon, epinephrine, cortisol, thyroxine, and growth hormone work in opposition to insulin

double sequential enzyme reaction

• glucose principle

glucose oxidase testing method

• impregnating testing area with a mixture of glucose oxidase, peroxidase, chromogen, and buffer

75-125 mg/dL glucose

• sensitivity for glucose

ketonuria

• when carbohydrate use is impaired, body uses fat for energy, producing ketones

type 1 diabetes mellitus

• testing for ketones is most valuable in the management and monitoring of this disease

• insulin is absent or insufficient, so glucose cannot be used for energy, the body switches to fat metabolism, producing large amounts of ketones

diabetic ketoacidosis

• increase accumulation of ketones in the blood

• electrolyte imbalance, dehydration, metabolic acidosis, diabetic coma

carbohydrate deficiency

• due to poor intake or absorption of carbohydrates

sodium nitroprusside reaction

• principle of ketones

acetoacetic acid

• reacts with sodium nitroprusside (nitroferricyanide) in an alkaline medium to produce a purple color

5-10 mg/dL acetoacetate

• sensitivity of ketone

acetest tablets

• confirmatory test for ketones