What is acromegaly due to? To what patients?What are the symptoms?
Pit tumor (micro or macro) causing overproduction of GH in adults (middle age)
Symptoms: overgrowth of soft tissues of face (nose and lips), hands, feet, and bones
What is gigantism due to? What are the symptoms?
Macroadenoma causing overproduction of GH in children (before closure of epiphysial endplate in puberty)
Symptoms: incredible height (7-8 feet), and sometimes acromegaly in adulthood
What is pituitary dwarfism due to? What are the symptoms?
Inability of pit to produce enough GH
Symptom: insufficient stature growth
What is Laron dwarfism due to? What are the symptoms?
Special subset of pit dwarfism due to lack of functioning GH receptors
Symptoms: insufficient stature growth and high GH because IGF-1 is not produced
What is wide-range hypopituitarism?
When a patient has a dysfunction of many cell types contained in the anterior pit
Why could macroadenoma cause increase in PRL?
If tumor is really pressing hard it is cutting flow of venous blood from the hypo to pit gland so dopamine is not making it to the pit
Are pit tumors usually cancerous/metastatic?
How do we treat thyroid tumors? What can this damage as collateral?
Radioactive iodide therapy to ablate the tumor
Salivary glands can be damaged also
How is thyroid storm treated during pregnancy? Why?
With PTU only during the first trimester (because it also causes liver damage) and then methimazole
What does eating cassava cause in people from Zaire?
They already are not ingesting enough iodide and by eating cassava they cannot pump iodide into the follicular cells of the thyroid gland, so this causes:
1. Low iodide
2. High amounts of TSH: thyroid gland growth = goiter
What is cretinism due to? Symptoms?
Insufficient amounts of thyroid hormones during development causing short stature and stunted brain development
What is newborn hypothyroidism caused by? How is it treated? Symptoms if not treated?
Inability to make thyroid hormones at birth
Treatment: administer thyroid hormones to prevent cretinism and growth defects (downturned mouth and dead eyes) FOR THE REST OF THEIR LIVES
What is endemic goiter caused by? 3 symptoms?
Not enough iodide in diet
1. Increased TRH
2. Increased TSH
3. Thyroid growth
What is Grave's disease caused by? More prevalent in what patients? Symptoms? Treatment? Side effects?
Autoimmune disease where antibodies (TSI: Thyroid Stimulating Igs) attack the TSH receptor of the thyroid gland stimulating it and causing high thyroid hormone production = hyperthyroidism and sometimes diffuse goiter
More common in women
10% of patients also have
Symptom: big eyes (proptosis), heat intolerance, tremor, weight loss, perspiration, diarrhea, oilier skin
Treatment: perchlorate, thiourea drugs (not PTU), surgery, and radioactive iodine (I131)
Side effects: weight gain
What is Hashimoto's thyroiditis caused by? Symptoms?
Autoimmune disease where antibodies attack thyroglobulin and break down the thyroid gland = hypothyroidism
Symptoms: cold intolerance, weight gain, cold clammy skin, slow reflexes and reactions, constipation
What is the Wolff-Chiakoff effect? How long does it last? Why? What is it often used to manage/prevent (2 things)? In what form?
Short-term effect of excess levels of iodide exerting negative feedback on the production/release of thyroid hormones at the point of thyroglobulin release of T3/T4 (vesicle formation). Relieved after 48 hrs due to increased export of iodide.
Solution of K+I- can be used to:
1. Manage or prevent thyroid storm
2. Decrease size (therefore vasculature) of thyroid and amount of THs
What are the long-term effects of excess iodide levels? Why?
Permanent iodide block and a goiter and hypothyroidism develop probably due to some underlying defect in thyroid
What are the medium-term effects of excess iodide levels? Why? How long does it take cells to recover?
Increased organification leading to increased MIT and DIT but decreased T3/T4 possibly because of decreased T3/T4 content of TGB
Takes cells 7-10 days to recover
What are the 3 types of patients to whom we recommend PTU instead of methimazole?
1. First trimester pregnant women
2. Thyroid storm
3. Allergic to methimazole
What is a thyroid storm? What can it be caused by? What is the main risk? Treatment?
Huge amount of TH entering your system at once.
Can be caused during neck surgery (may or may not involve thyroid), by surgeon causing a huge release by touching the colloid space that has months worth of hormones
Risk: ventricular fibrillation and heart attack. Very dangerous.
Treatment: PTU, lithium, and methimazole
What is a goitrogen?
Food containing TH production/release inhibiting agent
How long does it take for newborn hypothyroidism to be noticed? How come?
Few days because of T4 half life in newborn blood from mother
What other condition is often seen alongside Grave's disease? Why?
70% of patients also have Hashimoto's thyroiditis because different kinds of antibodies are being produced: some will activate some will destroy
People with this type of autoimmune disorder typically do not present with both conditions in full bloom at the same time, but one after the other: symptoms of hyperthyroidism would gradually diminish (except the exophthalmos might need to be surgically corrected) and the symptoms of Hashimoto's hypothyroidism would gradually begin to appear
Can iodide be used to treat hyperthyroidism? When?
Yes, in the short-term
Why does hyperthyroidism cause weight loss and hyperphagia?
Because excess TH causes an increase in the basal metabolic rate causing an increased caloric intake which is then burned fast:
1. Na+ is more permeable so the Na+/K+ ATPase channels are doing more work
2. Gut motility is increased
Why does hyperthyroidism cause heat intolerance? 2 reasons
1. Excess TH increases the basal metabolic rate
2. Excess TH causes an increase in uncoupling proteins: mitochondrial inner membrane proteins channels/transporters that are capable of dissipating the proton gradient generated by NADH-powered pumping of protons from the mitochondrial matrix to the mitochondrial intermembrane space. The energy lost in dissipating the proton gradient via UCPs is not used to do biochemical work. Instead, heat is generated.
What does a diffuse goieter mean?
Means the size increase is consistent all around the gland
What does constitutive production of a hormone mean? Eg?
Production without negative feedback.
Eg: endemic goitier
What is virilization?
Masculinization is the biological development of sex differences
What is the effect of the drug metyrapone?
Blocks 11-β-hydroxylase => cortisol/aldosterone decrease