Endocrinology Flashcards
Initial workup for adrenal incidentaloma?
- 1 mg overnight dexamethasone suppression test
- plasma aldosterone-plasma renin activity ratio
- urine metanephrines and catecholamines, (and serum metanephrines for high likelihood)
Features of adrenal incidentaloma that suggest malignancy?
- bilateral or large lesions >4 cm
- irregular or inhomogenous morphology
- contrast enhancement with delayed washout
- high-attenuation lesions >20 HU
When to remove adrenal incidentaloma?
- > 4 cm or if functioning
How do DPP-4 inhibitors work and what are two examples?
- inhibits the breakdown of GLP-1 and GIP, which leads to glucagon suppression, insulin release, and therefore decrease blood glucose
- ex. sitagliptin (Januvia) and linagliptin (Tradjenta)
Causes of stridor after thyroidectomy, and how to distinguish between them?
- immediately after extubation -> recurrent laryngeal nerve injury
- few hours after extubation -> wound hematoma compression
- greater than few hours after and preceded by paresthesias or muscle cramps -> likely 2/2 transient hypocalcemia (common 60-90% pts) or inadvertent parathyroidectomy
Etiologies of metabolic alkalosis with hypokalemia? How to distinguish?
- vomiting
- diuretic use
- abnormal sodium handling- Bartter or Gitelman
- urine chloride is low in vomiting because GI losses cause chloride to be reabsorbed by kidneys
- patients taking diuretics or who have abnormal sodium handling are unable to reabsorb it so they have high urine chloride
What endocrine screening do all new hypertensive patients require?
TSH
In amiodarone-induced thyrotoxicosis, radioactive iodine uptake levels are:
undetectable or low
TSH, T3 and T4 levels in euthyroid sick syndrome?
low T3 typically, normal T4 and TSH
Evaluation of thyroid nodule?
- TSH and thyroid u/s
- TSH low-> radioactive iodine scintigraphy
TSH normal or high- consider FNA based on size and u/s findings
3. radioactive iodine scintigraphy shows: hot nodule (hyperfunctioning): treat the hyperthyroidism
cold nodule (hypofunctioning or indeterminant): consider FNA based on size and u/s findings
Etiology of primary adrenal insufficiency (Addison’s Disease)?
- Autoimmune
- Infections
- Hemorrhagic infarction
- Metastatic
Clinical presentation of primary adrenal insufficiency?
- fatigue, weakness, anorexia/wt loss, salt cravings
- GI symptoms
- postural hypotension
- vitiligo or hyperpigmentation
- hyponatremia, hyperkalemia
- may lead to acute adrenal crisis: hypotension, shock ,abdo pain, AMS
Diagnosis of primary adrenal insufficiency
ACTH, serum cortisol, high dose ACTH stimulation test/cosyntropin
primary: low cortisol, high ACTH
secondary/tertiary: low cortisol, low ACTH
indications for parathyroidectomy in primary hyperparathyroidism
age >50 osteoporosis serum ca >1 mg the upper limit of normal urine ca loss >400/day renal insufficiency- CrCl <60 ml/min
In central (secondary) hypothyroidism, ex. pituitary tumor, what lab value do you use to titrate levothyroxine?
Free T4
TSH is usually low or inappropriately normal in central hypothyroidism, and does not respond to levothyroxine
Patient characteristics that put them at risk for thyroid cancer?
- ionizing radiation exposure (esp in childhood)
- family hx of thyroid cancer or thyroid cancer syndrome (MEN2, familial polyposis coli, cowden syndrome)
- Age <30 or Age >60
- Iodine deficiency
- elevated TSH (because a suppressed TSH would indicate a hyperfunctioning nodule, typically benign)
Nodule characteristics high risk for thyroid cancer?
- rapid growth
- hard/fixed nodule
- associated cervical lymphadenopathy
- obstructive sx. ex. hoarseness, dysphagia
- US size >1 cm, microcalcifications, hypoechoic, increased vascularity, infiltrative margins, length>width
What thyroid blood test is affected by OCPs?
Increased thyroid binding globulin will increase total T4
What other workup do patients with central hypothyroidism need?
They need evaluation for other pituitary hormone deficiencies (ACTH, growth hormone), as well as neuroimaging.
Glucocorticoid deficiency must be diagnosed in central hypothyroid patients prior to starting levothyroxine. If there is a glucocorticoid deficiency, and levothyroxine is rx to the patient prior to correcting this, you can precipitate an adrenal crisis.
Timeline of Sheehan’s syndrome? (Adrenal insufficiency after pregnancy)
Severe: days after pregnancy, presents with failure to lactate, lethargy, weight loss and lack of sexual hair
Mild: can be months to years after complicated pregnancy, milder sx.
Multiple hormone deficiencies including thyroid are common
How does opiate use affect gonadal function?
Secondary (central) hypogonadism -
Suppresses GnRH, causing low FSH, LH and testosterone.
Antibodies associated with LADA- latent autoimmune diabetes of adulthood (T1DM that occurs usually between age 35-50)
anti GAD- glutamic acid decarboxylase
anti ICA- islet cell antibodies
Features of painless thyroiditis?
- usually occurs in women >1 year after pregnancy, however can also occur in non-post partum women and men
- etiology: preformed thyroid hormone release
- 1-2 mos of mild hyperthyroid symptoms, followed by hypothyroid sx and recovery
- high thyroglobulin
- unlike Graves: usually NO exopthalamos, mild to no goiter, LOW uptake on radioactive iodine scan
How to treat myxedema coma?
IV levothyroxine, IV liothyronine and IV hydrocortisone because there is often also adrenal insufficiency
What can cause copper deficiency?
- gastric bypass surgery
- excessive zinc supplementation
- prolonged TPN
- malabsorptive diseases- celiac, IBD
Symptoms / clinical pres of copper deficiency?
- leukopenia
- anemia- macro/micro or normo cytic
- sx similar to b12 deficiency: neuropathy, ataxia, spasticity with weakness, positive Romberg, dorsal column disease
Treatment for osteopenia if Cr clearance is <30?
Denosumab/Prolia
bisphosphonates are contraindicated
Two most common causes of hypercalcemia, and how do they present differently?
- Hyperparathyroidism
- slow onset, gradual
- mild symptoms: constipation, fatigue, stones - HyperCa of malignancy, usually PTHrP
- rapid onset
- severe sx: confusion, muscle weakness, polyuria
How long on chronic steroids before the HPA axis is affected? How long after d/c steroids does it resolve?
> 3 weeks
resolves up to 6-12 mos later
Testosterone deficiency: diagnosis and treatment
diagnosis:
Total testosterone <300 measured between 7 and 10 am
tx: transdermal or IM testosterone replacement
