Endocrine Flashcards
Anyone with a thyroid nodule should get:
History and physical exam
Measurement of serum TSH
Ultrasound
Reasons for decreased C-peptide
Factitious hypoglycemia
Type 1 diabetes mellitus
Reasons for increased C-peptide
Insulinoma
Type 2 diabetes mellitus
Diagnostic threshold level for OGTT
200+ mg/dL (after two hours)
A positive thyroid antibody test suggests …
Autoimmune disorder (Hashimoto’s or Graves)
Hypothyroidism side effects
Everything slows down
Hyporeflexia
Slower brain
Fatigue
Weight gain (fluid)
Constipation
Menorrhagia
Easily chilled
Gestational diabetes screening for women with risk factors/history
Screen at first prenatal visit with OGTT
(risk factors same as diabetes, except age is 35 instead of 45)
Screen women with history 6-12 weeks postpartum using OGTT and lifelong every 3 years
Is there a poor or strong correlation between plasma and urine glucose?
Poor correlation (variable renal threshold)
If pituitary or hypothalamic disease is suspected (e.g. a young woman with amenorrhea and fatigue) what would you want to measure?
BOTH serum TSH and free T4
The most accurate method for evaluating thyroid nodules when TSH is normal or elevated is …
FNA biopsy (fine needle aspiration)
Uses ultrasound to guide
Reasons for decreased insulin
Diabetes mellitus
This medication inhibits extrathyroidal conversion of T4 to T3 and can cause T4 toxicosis
Amiodarone
Which is more likely to be cancerous, a “hot” or “cold” thyroid nodule?
Cold
Next steps if:
1.) TSH normal
2.) TSH high
3.) TSH low
1.) TSH normal - no further testing
2.) TSH high - Free T4 (determine degree of hypothyroidism)
3.) TSH low - Free T4 and T3 (determine degree of hyperthyroidism)
Primary labs for hyperthyroidism
Free T4 and T3
Once steady state, use TSH to monitor disease
What hormone is used in pregnancy tests?
hCG (human chorionic gonadotropin)
The precursor to testosterone and estrogen is …
DHEA
Most common cause of hyperthyroidism
Graves disease
Thyroid disease in the ambulatory setting can be excluded if this test is normal
TSH levels
Normal fasting blood glucose
60-100 mg/dL
Ingestion of this vitamin can interfere with TSH lab levels
Biotin
When to take a pregnancy test
hCG appears 3-7 days after conception
Not good to do before first missed period
Casual glucose threshold (any time of day regardless of food intake)
<200 mg/dL
What are the three points of Whipple’s triad?
Symptoms consistent with hypoglycemia
A low plasma glucose concentration (<50 mg/dL)
Immediate relief of symptoms with IV glucose
Most important test to assess thyroid
TSH level
Anterior pituitary hormones
TSH
LH
FSH
(also GH and ACTH, but not talked about here)
Diabetic and pre-diabetic levels for HbA1c
Diabetic = 6.5% or more
Pre-diabetic = 5.7 to 6.4%
If TSH is elevated, order this test …
Free T4
Non-diabetic reasons for increased blood sugar (hyperglycemia)
Acute stress response
Corticosteroids
Test levels of this to assess ED/fertility in men, PCOS/masculine features in women, or early/precocious puberty in teens
Testosterone
Estrogen levels can be used to monitor these four things
Puberty
Menstruation
Fertility
Menopause
Reason for HbA1c to be elevated
Newly diagnosed diabetic patient
Reasons for decreased TSH
Hyperthyroidism
This test is done when TSH is low to determine the functional status of thyroid nodules
Scintigraphy (aka thyroid uptake, radionuclide thyroid scan)
Describe myxedma coma
Medical emergency with high mortality rate
Severe hypothyroidism
Periorbital edema, puffy, dull, dry face, hair thinning
Low T4, TSH variable
Reasons for non-diabetic low blood sugar (hypoglycemia)
Excessive alcohol intake
Hepatitis
Anorexia nervosa
Tumors of the pancreas (insulinoma)
ADA screening recommendations for diabetes or pre-diabetes
Don’t screen for DM1
Screen all adults overweight with at least one other risk factor
If no risk factors, screening begins at 45 (fasting plasma glucose recommended)
Hyperthyroidism side effects
Everything speeds up
Skin smooth and moist
Hyperreflexia
Racing mind
Weight loss (10 lbs)
Low volume frequent stools
Oligomenorrhea
Heat intolerance
Arrythmias (Afib)
In hypothyroidism would TSH and free T4 be elevated or decreased?
TSH up
T4 down
Risk factors for diabetes (11)
- Age 45+
- BMI 25+ (overweight)
- 1st degree family history DM
- Physical inactivity
- High-risk ethnic group (Black, Hispanic, Native American, Asian American, Pacific Islander)
- History of delivering fat baby (9lbs+)
- HTN (140/90)
- Dyslipidemia (HDL <35 and/or TGs >250)
- Previous impaired glucose tolerance or impaired fasting glucose
- PCOS
- History of vascular disease
Which is more likely to require FNA, a hyper or hypo functioning thyroid nodule?
Hypo
Reasons (3) for increased TSH
Primary hypothyroidism
Thyroiditis
Severe and chronic illness
Screening recommendations for microalbuminuria and what med to use to treat
Annually
Two out of three tests positive = start patient on an ACE!
HbA1c level goal for diabetes patients
7%
Two reasons to order a TPO antibody
Goiter (enlargement of thyroid gland)
Subclinical hypothyroidism or postpartum thyroiditis
USPSTF rating, age range, and frequency for prediabetes and DM2
B
Age 35-70
Every three years
These four tests can be done to differentiate type one from type two diabetes
Insulin assay
C-peptide
Islet cells (antibodies?)
GAD 65 antibodies
Most patients with hyperthyroidism caused by nodular goiter or Graves have greater increase in …. (T3 or T4?)
T3
(watch out for T3 toxicosis)
Describe a thyroid storm
Rare life threatening condition, severe or exaggerated clinical manifestations of thyrotoxicosis
Hyperthyroidism
C-peptide levels correlate with … levels in the blood
Insulin (degree of insulin insufficiency)
Gestational diabetes screening for women without risk factors or history
Screen at 24-28 weeks with OGTT
HbA1c measures average blood glucose levels over this period of time
120 days (lifespan of red blood cell)
Primary lab to monitor hypothyroidism
TSH
If patient has symptoms of hyper or hypothyroidism but a normal TSH result, what is your next step?
Measure serum free T4
Blood levels of hCG for negative, indeterminate, positive pregnancy tests
Negative = under 5
Indeterminate = 5-25
Positive = over 25
Patients with low serum TSH but normal free T4 and T3 have …
Subclinical hyperthyroidism
TSH is released from the …. and T3, T4 are released from the ….
TSH from pituitary
T3,T4 from thyroid
ADA diagnostic criteria for diabetes mellitus
A. Symptoms of diabetes and a casual plasma glucose 200+ mg/dL
B. Fasting plasma glucose >125 mg/dL
C. OGTT 200+ mg/dL
D. HbA1c 6.5+%
In absence of unequivocal hyperglycemia, DM dx must be confirmed on a subsequent day by measuring any one of b, c, d.
Posterior pituitary hormones
ADH
Oxytocin
Reasons for increased insulin
Insulinoma
Obesity
What TSH level (high, normal, low) increases the possibility that a thyroid nodule is hyperfunctioning?
Low TSH
Insulin assay should always be performed in conjunction with this test
Blood glucose
Cortisol levels are highest at this time of day
6am to 8am
Except for lab error, all patients with low TSH and high free T4 and/or T3 have ….
Primary hyperthyroidism
It is generally accepted that a woman has reached menopause when …
No menstruation for a year
AND
FSH reaches 30+ mIU/mL
What imaging should be used to screen for non-palpable thyroid cancers?
None, don’t screen if it’s non-palpable
(but if palpable it’s ultrasound)
