ENDOCRINOLOGY Flashcards
Explain the renin aldosterone path–how does this contribute to secondary hypertension
Low CO –> low renal perfusion –> high renin –>high angiotensin I –> high angiotensin II –>high aldosterone –> retention of sodium/water (EXCRETION of K)–>high BP
SECONDARY HTN
(1) renal artery fibromuscular dysplasia
- young woman w/ new or difficult to control HTN
- LOW perfusion to kidneys –>so HIGH renin
-systolic abdominal bruits +/- low/normal potassium
(2) Primary hyperaldosteronism
-High aldosterone
-LOW renin (note Cushing syndrome assoc w/suppressed renin)
-low potassium
What are ekg findings of hyperkalemia
(1) peaked T waves (also see w/MI, brain hemorrhage)
(2) decreased amplitude p waves
*NOTE: ekg findings for HYPOkalemia –>U wave (also see w/digoxin, amiodarone, bradycardia)
When is RAIU high? Low?
RAIU distinguishes Graves from other forms of hyperthyroidism
RAIU HIGH (<30%)
-Graves
-Tx: methimazole, Propylthiouracil (Pregnancy=PTU)
RAIU LOW
-acute thyroditis (painful)
-iodine excess/ amiodarone deficiency (usus geographic change)
-struma ovari
-Tx: BB (atenolol) or prednisone (if tenderness)
NOTE:
1) Thyrotoxicosis describes high levels of circulating thyroid hormones (T4 and T3) from any cause.
2) Thyrotoxicosis is diagnosed with a low TSH and elevated free T4 and/or total T3.
3) Thyroid scintigraphy with RAIU can verify the cause; HIGH w/Graves and LOW in other causes
4) Thyroid-stimulating immunoglobulin (TSI) or thyrotropin (TSH) receptor antibodies (TRAb) measurement can identify Graves disease (with high sensitivity and specificity)
When is thyroglobulin high? low?
Thyroglobulin is only high for endogenous hyperthyroid conditions. For all hyperthyroid (ie factitious) will be LOW
What decr levothyroxine absorption (makes hypothyrodism worse)
1) CALCIUM
2) IRON
3) Also:
-PPIs
-Binding agents (sucralfate cholestyramine)
-SSRIs, sertraline (esp if started/stopped/dosage change)
What is tx for hyperthyrodisim
Three treatment modalities for hyperthyroidism are (1) thionamides (methimazole and propylthiouracil), (2) radioactive iodine ablative therapy, and (3) thyroidectomy; the choice of treatment depends on the cause of the hyperthyroidism and patient preference
-1st line: methimazole
-IF pregnant: Propylthiouracil. Radioactive iodine is contraindicated
-IF thyroid storm: Propylthiouracil (preferred) or methimazole
-IF thyroiditis: NSAIDS
-IF Severe Graves ophthalmopathy: Methimazole or thyroidectomy. Avoid radioactive iodine
Describe testing/diagnosis for thyroid nodules?
When a nodule is discovered, assess thyroid function with a serum TSH level.
1) IF Low TSH (hyperthyoidism) → radioisotope scan scintigraphy
2) IF Normal or high TSH (hyPOthyroidism) → obtain ultrasonography.
3) FNAB is indicated after u/s:
- nodules >1 cm w/ suspicious features on u/s
- nodules <1 cm w/ RFs for thyroid cancer or suspicious ultrasound characteristics
Desc metabolic/lab findings with adrenal insufficiency
1) LOW aldosterone
* low aldosterone: low Na reabsorption/ low H/K excretion
- hyponatremia/hypotension, hyperkalemia/metabolic acidosis
- glucocorticoid deficiency
2)ELEVATED ACTH (primary only)
-hyperpigmentation (tanned)
3) Anion GAP
-pre-renal state
When do you measure T3
ONLY for HYPERthyroidism
-Meas if FT4 normal despite suppressed TSH
How do you diagnose adrenal insufficiency?
1) 8 AM Cortisol test
-IF High (>15) –>NOT adrenal insufficiency (AI)
-IF Low (<3) –>AI
-IF equivocal (3-15) –>ACTH Stim Test
2) ACTH Stim test (ONLY if cortisol 3-15)
-IF peak cortisol high (>18) –>NOT AI
-IF peak cortisol low (<18) –> AI
3) MEASURE ACTH (after cortisol test, and +AI)
- IF High –>primary AI
-IF Low –>secondary AI
What is the management for DKA?
1) FLUIDS
- Give 0.9% saline IV at 1 L/h
- SWITCH to 0.45% saline if corrected serum sodium level becomes normal or high.
2) GLUCOSE (goal 150-200)
- Give IV insulin
- SWITCH to 5% dextrose (w/ 0.45% saline) if plasma glucose 200 mg/dL (or 300 mg/dL in HHS)
3) POTASSIUM (goal 4-5 range)
-If serum potassium LOW (<3.3 mEq/L), do not start insulin; instead, give IV potassium chloride until level is >3.3 mEq/L. Then Add 20-30 mEq of potassium chloride to each liter of IV fluids to keep serum potassium level in the 4-5 mEq/L range.
-If serum potassium HIGH ( >5.2 mEq/L), do not give potassium chloride; instead, start insulin and IV fluids and check serum potassium level every 2 hours.
What is DKA? What is HHS?
HHS
-Hyperglycemic hyperosmolar syndrome
-Occurs with extreme hyperglycemia (>600 mg/dL) in OLDER pts w/ DM2
-Labs: no or low serum levels of ketones, and a relatively normal arterial pH and bicarbonate level.
DKA
-hyperglycemia, ketosis, and hypovolemia.
-Labs: plasma glucose level ≥250 mg/dL, arterial blood pH ≤7.30, bicarbonate level ≤15 mEq/L, increased anion gap, and positive serum ketone levels.
What 3 labs used to diagnose DM2? Do you have to confirm abnl results? What is 1 scenario where abnl results do NOT have to be repeated?
Diabetes mellitus can be diagnosed by an abnormal result on one of the following screening tests:
(1) hemoglobin A1c >6.5
(2) fasting plasma glucose >126
(3) oral glucose tolerance test.
** Abnl testing needs to be confirmed 2x.
** A single plasma glucose measurement of
> 200 mg/dL + plus symptoms is also diagnostic for DM2
How do you control triglycerides in DM2?
Triglycerides related to glucose control!
-If glucose control poor, triglycerides wil be high
-If triglycerides high and LDL normal in DM2–start statin!
Describe lab values of hypocalcemia caused by LOW PTH
-low PTH
-low Calcium
-High Phosphate
What are hormones of anterior pituitary. Dx of excess?
“FLAT PIG”
FSH
LSH
ACTH –> cortisol excess, aldosteronism
TSH
Prolactin –>Prolactinoma (decr LH/FSH)
GH –>acromegaly
How do you diagnosis cortisol excess
Cortisol excess
-pituitary dependent: Cushing disease
-NOT 2/2 pituitary: Cushing Syndrome
DIAGNOSING CORTISOL EXCESS:
1) First-line: overnight low-dose dexamethasone suppression test, 24-hour urine free cortisol measurement, and late-night salivary cortisol measurement; 2 or 3 tests must be abnormal.
2) Measure ACTH; determine whether the patient has adrenocorticotropic hormone-dependent or -independent Cushings.
How do you treat cortisol excess?
Surgical resection is the definitive treatment
How do you dx aldosterone excess?
SUSPECT in pts w/resistant HTN +/- low normal K
1) Order plasma renin activity
-plasma aldosterone concentration (PAC)/PRA (plasma renin actvitity)
A plasma aldosterone–plasma renin activity ratio >20, with a plasma aldosterone level >15 ng/dL, strongly suggests primary hyperaldosteronism.
