Endocrine labs Flashcards
Diabetes Mellitus, What types? What are they specific to?
Type I
- Usual onset under the age of 30
- Autoimmune destruction of the pancreatic islet B cells
- Insulin dependent
Type II
- Most common endocrine disorder in the US
- Tissue insensitivity to insulin
- Obesity and adult onset
Gestational Diabetes
- 30-50% change of developing type 2 diabetes later.
What is glucose used to screen for?
Glucose is used to screen for diabetes
Usually is measured fasting, and then a 2 hour post prandial test
pearl- if glucose is abnormal, - first assess if it was a fasting or non fasting glucose.
- fasting should not include coffee or additives - no caffeine. Water and medications only.
What is the best indicator for glucose homeostasis?
Fasting glucose.
Fasting Glucose parameters and facts. what is a normal fasting glucose? What fasting glucose indicates diabetes?
- Fasting glucose is the best indicator for glucose homeostasis
- It may be used to monitor therapy in diabetics
- Normal fasting glucose is considered less than 110.
- there is lab to lab variation though
- Fasting glucose of greater than 110 and less than 126 is pre-diabetes
- also called impaired fasting glucose
- Fasting glucose greater than 126 on 2 seperate occasions is diagnostic for diabetes.
What is the 2 hour post prandial glucose test?
- a 2 hour post prandial glucose test measures glucose 2 hours after a meal
- Meal acts as glucose challenge
- insulin normally secreted after a meal, glucose should return to premeal rane in 2 hours
- Diabetes- glucose level remains elevated at 2 hours
- Normal <140mg/dl
- If greater than 200 mg/dl - confirms diagnosis of diabetes
- If 140-200mg/dl follow with glucose tolerance test.
What is the glucose tolerance test? when would you use it?
- The glucose tolerance test is usually a 2-3 hour test some people still do 4 hours
- When to order
- pregnancy/women with history of large birth weights or stillborns
- abnormal 2 hour post prandial glucose, not diagnostic of diabetes (140-200)
- Obese patients
- History of recurrent infections
- Patients with delayed healing of wounds.
What are the normal results for a glucose tolerance test? what is diagnostic of diabetes?
- Normal
- fasting <110mg/dl
- 1 hour <200
- 2 Hour <140
- 3 hour 70-115mg/dl
- Criteria for diagnosis of diabetes
- Fasting glucose is greater than 126 mg/dl
- 2 hour glucose > 200mg/dl
What are other factors that can affect glucose levels?
- Stress - releases cortisol which acts to increase glucose via gluconeogensis and glycogenolysis. It also decreeases glycogenesis.
- Caffeine can elevate glucose
- IV fluids containing dextrose - do not give dextrose containing fluids to diabetic patients
- pregnancy
- durgs - prednisone, and estrogens
- smoking
What patient education is needed prior to glucose testing?
- You should be fasting for 8-12 hours
- Do not smoke during glucose tolerance test - this can elevate glucose and give an inaccurate reading
- Do not exercise 24 hours before the glucose tolerance test.
What is Glycosylated Hemoglobin? what does it tell you? What is a nomral range?
Glycosylated Hemoglobin is HGA1c. It tells you the measurement of glucose levels over the last 3 month period.
Red blood cells contian HgA1c and binds strongly to glucose
120 day lifespan of RBC gives us a 3-4 month average of what their glucose levels have been. This is indicative of glucose control.
- Normal levels 4-5.7%. Greater than 6.5% is considered poor control but there is some debate to this.
- Fasting is not required for this test.
A1c results for normal, prediabetics, diabetics.
- Normal less than 5.7%
- pre diabetic 5.7%-6.4%
- Diabetic - 6.5% or higher.
What are the diagnostic criteria for diabetes?
A1c is greater than 6.5%
Fasting glucose is greater than 126 mg/dl or
Oral glucose tolerance test with 2 hour level at 200 mg/dl or higher.
What is ketoacidosis?
- Ketoacidosis is a diabetic emergency
- Type 1 diabetes is most common and starting to see it in some type ii diabetics.
- Basically it is an insulin deficiency resulting in protein breakdown and increased hepatic production of glucose
- Lipolysis occurs and free fatty acids are converted to ketone bodies (beta-hydroxybutyric acid and acetoacetic acid)
- This results in metabolic acidosis because the ketones are acidic
- Presents with dehydration, lethargy, acetone smelling breath, occasionally a coma.
What are the lab fidings in ketoacidosis?
- Glucose is greater than 300 mg/dl
- Low bicarbonate (0-15mEq/L)
- Low pH (lower than 7.2)
- Na and K levels may be low, normal or high. Depends on what phase they are in.
How is potassium affected in ketoacidosis?
- Initially, insluin deficiency usualyl causes elevated potassium levels due to extracellular movement of potassium. intracellular to extracellular
- Hypertonicity and acidosis cause K to move from intraacellular to extracellular space
- Total K depletion occurs the longer ketoacidosis progresses - results in cardiac dysrythmia
- Pearl- inital treatment of ketoacidosis includes insulsin administartion with potassium
- This is because there is a potassium depletion
- but mainly because potassium will help insulin go into the cell.
