Thyroid, Pancreatic, GI Function
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Basal metabolic rate (BMR) and protein bound iodine (PBI) were early methods of measuring thyroid function. Which one measures hormonal and non-hormonal iodine, is used as a measure of T4, and involves precipitating proteins which contain organic iodine and digesting them so that the iodine can be measured?
PBI
Iodine is used as a catalyst in the _____ by arsenic. Following this, the disappearance of _____ is measured. Why would an MT not want to use this method?
Reduction of ceric ion yellow color Iodine contamination Iodine contamination is an issue
The PBI is decreased in _____ (3). PBI is increased in _____ (4)
Decreased • Hypothyroidism • Thyroidectomy • Antithyroid drugs Increased: • Hyperthyroidism • Pregnancy • Thyroiditis • Iodine contamination
How can one tell there is iodine contamination?
T3 and T4 values are normal PBI is elevated
_____ involves two phases: column chromatography and colorimetry. In the chromatography phase, serum _____ so that thyroxine _____. The solution is poured onto a _____ and _____.
• Thyroxine-by-Column • is allowed to stand • dissociates from proteins • T4 ion exchange column • Thyroxine binds to the resin
Pituitary Cushing’s syndrome is more common in _____ than _____. This is not the case in _____ Cushing’s. How is the presence of Cushing’s detected?
• Women than men, Ectopic • A 48-hour dexamethasone suppression test followed by a CRH stimulation test. • SUPPRESSION: • Normal patients, Pseudo-Cushing’s syndrome patients • IF NO SUPPRESSION • 24 Hour urine-free cortisol is done • Low dose dexamethasone suppression test #2 is done • Normal 24hr urine free cortisol that suppresses after low dose dexamethasone • Elevated 24hr urine free cortisol that does not suppress after low-dose dexamethasone • Another test is the combined **desmopressin plus CRH** stimulation test. • A dramatic rise should be seen in the case of a pituitary tumor but not an ectopic tumor. Normal 24-hour urine free cortisol that suppresses after low-dose dexamethasone: NOT CUSHING’S • Elevated 24-hour urine free cortisol that DOES NOT suppress after low-dose dexamethasone: CUSHING’S
Describe the laboratory protocol for investigation of Addison’s disease.
• Draw blood for ACTH and baseline cortisol • Inject synthetic ACTH (cortrosyn and measure cortisol at 30 and 60 minutes) • Normal ACTH with increase in cortisol = NOT Addison’s disease • Low ACTH with blunted cortisol response to ACTH • Secondary adrenal insufficiency or atrophy due to chronic steroid therapy • Increased ACTH with blunted cortisol response to ACTH • Addison’s disease
• What is pheochromocytoma? • What is VMA? • What test can be used to identify Pheochromocytoma? • What is the purpose of this test?
• Hormone-secreting tumor of the adrenal glands. Commonly affects patients 20-50 but can occur at any age. • Urinary vanillylmandelic acid • Exclusion of pheochromocytoma diagnosis in hypertensive patients and patients with borderline changes in plasma catecholamines or urinary catecholamine metabolites
• What is the pancreas? • Which portion of the pancreas may lead to duodenal disease? • What is the purpose of the GI system?
• Large endocrine and exocrine gland located outside GI system • Head (larger end). Tail is the smaller end. • Big system – mouth to rectum. Digestion of starch, lipids, proteins, carbs, nucleic acids into molecules that can be absorbed and used in the body.
• What does the pancreas secrete? (Endocrine, Exocrine) • What are two important pancreatic cell types and what do they secrete?
• Hormones, Enzymes • Alpha and beta cells: insulin and glucagon (glycogenolysis)
What are two non-insulin/glucagon hormones of the pancreas?
Somatostatin Pancreas polypeptide
Pancreatic activity is controlled by
secretin and cholecystokinin
Two important enzymes of the pancreas (exocrine) are
Amylase Lipase
Secretin
• Hormone secreted by the duodenum in response to acidity (from the stomach reaching the duodenum). Stimulates liver and pancreas to secrete (more amylase and lipase, assumedly)
CCK
Stimulates release of digestive enzymes and bile from the pancreas and gallbladder. Hunger suppressant.
Greasy foul smelling stools may indicate…
malabsorption
What does Amylase do? What does Lipase do?
Amylase: aids in starch and glycogen breakdown Lipase: breakdown of triglycerides
Amylase is elevated in 75% of _____. It may also be elevated in what conditions?
Acute hepatitis patients. • Hepatitis, cirrhosis • Mumps, salivary gland irritation • Renal insufficiency, intestinal obstruction
Sample of choice for Tests of Pancreatic Function
• Serum • Heparinized plasma • Lithium/sodium heparin probably both okay • Depends on other tests that are ordered
True increases in serum amylase will also show increases in _____ amylase.
urine
Salivary amylase isoenzymes include _____. Pancreatic amylase isoenzymes include _____.
S1, S2, S3 P1, P2, P3
What can falsely increase pancreatic function tests?
• Morphine • Opiates • Constriction of Pancreas
What can falsely decrease amylase test results? What can lead to *no* increase in amylase results?
Elevated trigs: acts to suppress or inhibit amylase Chronic pancreatitis/pancreatic tumor
What can increase lipase results?
Increase in acute and chronic pancreatitis (Also ulcer, intestinal obstruction, acute cholecystitis)