Hypothalamic-Pituitary Axis Flashcards
(213 cards)
1
Q
Which type of cells are rarely clinically functional in an adenoma?
A
Gonadotrophs
2
Q
From where is IGF-1 secreted? What triggers this?
A
Liver, along with other somatomedins in response to growth hormone
3
Q
Rate limiting step of cholesterol biosynthesis
A
Cholesterol side chain cleavage enzyme (P450scc/CYP11A1/desmolase) cleaves off 6-carbon side chain to yield pregnenolone
4
Q
First step of cholesterol biosynthesis
A
Cholesterol side chain cleavage enzyme (P450scc/CYP11A1/desmolase) cleaves off 6-carbon side chain to yield pregnenolone
5
Q
21-alpha-hydroxylase deficiency- presentation
A
- Decreased cortisol
- Increased androgens causes virilization of female (shunting)
- Decreased aldosterone leads to salt wasting
6
Q
Where does vitamin D regulate intestinal calcium absorption?
A
Duodenum
7
Q
Graves’ disease- ultrasound findings
A
Diffuse enlargement with high vascularity
8
Q
Sheehan’s syndrome- presentation
A
Postpartum hypopituitarism. Acute presentation may include failure to lactate and hypotension/tachycardia (even after correction for blood loss and hypoglycemia). Presentation may also be chronic/late.
9
Q
What is familial hypocalciuric hypercalcemia?
A
A rare disease caused by an inactivating mutation of CaSR. Chief cells do not sense high free calcium, so they keep secreting PTH. Kidneys keep reabsorbing calcium.
10
Q
What is cushinoid syndrome?
A
Iatrogenic cause due to oral corticosteroids for immune suppression
11
Q
Hypothyroidism- symptoms
A
Weakness, lethargy, somnolence, slow speech, cold intolerance, memory impairment, constipation, weight gain, dyspnea, menorrhagia, hair loss, myxedematous edema
12
Q
123-iodine scintigraphy- toxic multinodular goiter findings
A
Non-uniform uptake with hot and cold areas. Uptake in upper normal or mildly elevated range
13
Q
Conn syndrome- causes
A
adrenal adenomas, adrenal hyperplasia, aldosterone-producing adrenocortical carcinoma, familial hyperaldosteronism, ectopic aldosterone-producing tumors
14
Q
What is hypercalcemia of malignancy?
A
Malignant tumor secretes PTHrP, excess calcitriol production, or osteolytic bone metastases
15
Q
Acromegaly- diagnosis
A
Serum IGF-1 level or lack of GH suppression during oral glucose tolerance test; MRI to confirm
16
Q
What is sacrificed in a radical lateral dissection of the neck?
A
sternocleidomastoid, CN-XI, internal jugular vein
17
Q
What do acidophiles in the pituitary gland secrete?
A
Prolactin and growth hormone
18
Q
Pheochromocytoma- classic triad
A
1) Sustained or paroxysmal HTN
2) Headache
3) Generalized sweating
19
Q
M1CR ligand and function
A
MSH and ACTH are ligands; simulates melanin production
20
Q
Adrenal cortical adenoma pathophysiology
A
Well defined, may be encapsulated, yellow to black color, rarely foci of necrosis. Neoplastic cells resemble normal cells. Clear, lipid-filled cells in sheets/nests. Uninvolved gland shows lipid-depleted, compact cells.
21
Q
Pheochromocytoma cell type
A
Tumor of catecholamine-producing chromaffin cells
22
Q
Enzyme that changes steroid from glucocorticoid path to androgen path
A
17,20-desmolase
23
Q
Most common cause of primary hyperparathyroidism
A
Solitary single adenoma
24
Q
Anaplastic/undifferentiated thyroid carcinoma- presentation
A
Very poor prognosis. Highly aggressive tumor in the elderly. Often kills by direct airway invasion.
25
Diabetes insipidus- presentation
Polyuria, polydipsia, hypernatremia, high plasma and low urine osmolality
26
11-beta-hydroxylase deficiency
- Decreased cortisol
- Increased mineralocorticoid activity (non-aldosterone mineralocorticoids with loss of negative feedback by aldosterone; elevated DOC [protein S])
- Increased androgens in utero
27
Blood supply to adrenal glands
Superior (from aorta), middle (from renal), and inferior (from renal) adrenal arteries
28
Inheritance pattern of congenital adrenal hyperplasias
Autosomal recessive
29
Neuroblastoma- presentation
- Infant/child
- abdominal mass
- fever
- weight loss
- opsoclonus myoclonus syndrome (OMS)
- Secretion of vasoactive intestinal peptide (VIP)
30
Factors regulating prolactin secretion
Releasing factors:
Oxytocin (need milk), TRH, others
Inhibiting factors:
Parvocellular dopamine, prolactin negative feedback on lactotrophs and activation of arcuate nucleus for DA secretion
31
PTH function
1) Increase DCT reabsorption of calcium (TRPV5)
2) Inducer of 1-alpha-hydroxylase to catalyze final step of calcitriol synthesis from calcidiol
3) Stimulates clearance of renal phosphate
4) Stimulates activity of osteoclasts by inducing RANKL expression in osteoblasts
32
Thyroid surgery complication causing breathy hoarseness
Unilateral recurrent laryngeal nerve injury
33
Pre-biosynthetic step of steroid hormones that is a rate-limiting factor
Transport of free cholesterol across outer mitochondrial membrane by steroidogenic acute regulatory protein (StAR)
34
How do the parathyroid glands sense calcium?
Calcium-sensing receptor (CaSR) on chief cells
35
What do you think when you see 2 or more parathyroid adenomas?
MEN1
36
MEN2 genetics
Autosomal dominant pattern. Gain-of-function RET mutation (chromosome 10). RET is a receptor tyrosine kinase. Activates MAPkinase cascade. Mutation causes constitutive growth signal in absence of GDNF (ligand).
37
Prolactinoma treatment
Dopamine agonists are first line.
- Cabergoline
- Bromocriptine
38
LH/FSH deficiency- presentation in women
Amenorrhea/oligomenorrhea, infertility, breast atrophy, vaginal dryness; note- no change in pubic and axillary hair (only source of androgens is adrenal gland, which is unaffected)
39
Common cause of gigantism
Growth hormone excess (often a GH/PRL adenoma) prior to epiphyseal plate closure
40
Where does RANKL bind?
Pre-osteoclasts, causing them to mature
41
Hashimoto's thyroiditis- pathology
- Glandular enlargement (diffuse goiter)
- Lymphocytic infiltrate with germinal centers
- Atrophic follicles
42
What is the pyramidal lobe?
Most caudal remnant of the thyroglossal tract, present in 1/3 of normal subjects
43
What is pseudohypoparathyroidism?
Receptor mutation causes PTH resistance
44
Hypophysitis- pathophysiology
Lymphocytic or granulomatous (TB/sarcoid)
45
What is MEN2A ?(Sipple syndrome)
Medullary-thyroid carcinoma (amyloid-producing) with pheochromocytoma and hyperparathyroidism
46
Graves' disease presentation
Nervousness, fatigue, weakness, sweating, heat intolerance, tremor, hyperactivity, palpitations, appetite decrease, weight loss, menstrual disturbance, Graves' opthalmopathy (variant of lid lag sign of thyrotoxicosis), Graves'-associated dermopathy (pretibial myxedema)
47
Lipoid congenital adrenal hyperplasia
Rare; accumulation of fatty deposits in the adrenal gland on biopsy due to accumulation of cholesterol. Genetic defects in StAR or cholesterol desmolase.
48
What metabolite is used to determine vitamin D deficiency?
Calcidiol (25-hydroxycholecalciferol, made in the liver from vitamin D3)
49
Central compartent of neck- level and boundaries
Level VI; hyoid bone (superiorly), carotid arteries (laterally), innominate artery (inferiorly)
50
Remnants of the thyroglossal duct that do not degenerate
Thyroglossal duct cysts, ectopic thyroid gland
51
Cushing syndrome- pathophysiology
Systemic disease due to chronic glucocorticoid excess
52
Thyroid hormone synthesis
Iodide is taken up from serum by the sodium-iodide transporter (NIS). Thryoglobulin is synthsized and exocytosed into the follicular lumen (colloid). Free iodide is transported into the follicle by pendrin, and it is oxidized to iodine by thyroid peroxidase (TPO). Iodination of thyroglobin tyrosine residues generates monoiodothyronine (MIT) or diiodothyronine (DIT). Conjugation of two of these products generates T3 or T4. If the MIT is the inner tyrosine, then it is inactive reverse T3. Iodinated is endocytosed, fusing with the lysosome to form the lysoendosome. Proteolysis liberates T3, T4, and RT3.
53
What non-IGF-1 receptor does IGF-1 bind?
Insulin receptor (insulin-like effects)
54
Where is calcium reabsorption hormonally controlled? What is the name of the channel?
In the distal convoluted tubule via TRPV5 (upregulated by PTH)
55
Pituitary apoplexy- pathophysiology
Sudden hemorrhage, often secondary to adenoma as it lays down new, leaky vessels
56
Fludrocortisone use
Low aldosterone activity (high affinity for mineralocorticoid receptor)
57
Effect of growth hormone on blood glucose
Diabetogenic: decreases glucose uptake by muscle and adipose, increases lipolysis
58
123-iodine scintigraphy- Toxic adenoma/nodule findings
Single hot nodule, suppression of the rest of the thyroid gland, uptake generally in normal range
59
What/where are the magnocellular neurons?
They originate in the paraventricular and supraoptic nuclei of the hypothalamus and go through the infundibulum to the neurohypophysis. They synthesize and secrete ADH and oxytocin
60
Aromatase actions
1) Androstenedione to estrone
| 2) Testosterone to estradiol
61
What blocks Levothyroxine absorption?
Calcium, soy, iron (CSI)
62
Metabolic effects of cortisol
- diabetogenic, mobilizing glucose
- mobilizes amino acids and glycerol backbones for gluconeogenesis
- "planning for stress"
63
Embryological origin of the neurohypophysis
Diencephalon; evagination termed the infandibulum
64
Medullary thyroid carcinoma- pathology
Organoid appearance with nests and cords. Immunostain for calcitonin.
65
Factors that regulate growth hormone release
Stimulatory: GHRH, ghrelin, low glucose, low FFAs, fasting, puberty, hormones, exercise
Inhibitory: somatostatin, GH and IGF-1 (negative feedback), high glucose, high FFAs, obesity, pregnancy
66
Medications for acromegaly
Octreotide and lanreotide (somatostatin analogs), pegvisomant (mutated GH receptor), cabergoline (only on STEP)
67
123-iodine scintigraphy- procedure
Give oral dose of iodine, then scan in 24 hours. Measure 24-hour uptake in thyroid.
68
Pituitary macroadenoma- presentation
1) Hormone excess/deficiency
2) Bitemporal hemianopsia
3) Headache (dura stretching)
4) Hydrocephalus (compression of CSF system)
5) Diplopia (CN-III) or other cranial nerve palsies if there is lateral extension
69
Pheochromocytoma- lab findings
- Elevated plasma metanephrines
- Elevated 24-hour urinary catecholamines and metanephrines
- Homovanillic acid and vanillylmandelic acid
70
What medications increase levothyroxine requirements?
Estrogen, antidepressants, anti-seizure meds, reflex meds
71
Congenital defect associated with hypoparathyroidism
DiGeorge syndrome
72
Hyperparathyroidism- presentation
Hypercalcemia symptoms, fractures, osteitis fibrosa cystica, GI symptoms, neuropsych, HTN, shortened QT, nephrolithiasis, band kerotopathy
73
Adrenal cortical carcinoma- hereditary syndromes
Li-Fraumeni, Beckwith-Wiedemann, MEN1
74
Hypoaldosteronism- diagnosis
History, plasma renin activity, serum aldosterone, serum cortisol
75
Hashitoxicosis- presentation
Similar to Graves' at first (may even have antibodies) but then patients become hypothyroid due to changes in the immune reaction
76
What happens when the Rathke's pouch fails to regress?
Pharyngeal hyopphysis, Rathke cyst, craniopharyngioma (benign)
77
Conn syndrome- treatment
Surgery is ideal if unilateral. Medications include mineralocorticoid antagonists (spironolactone, epleronone) and potassium-sparing diuretics (amiloride, triamterene)
78
Mineralocorticoid zone
Zona glomerulosa
79
Sources of cholecalciferol (vitamin D3)
1) de novo from cholesterol
| 2) dietary (fish, eggs, fortified milk)
80
Hypoaldosteronism- causes
- Hyporeninemic hypoaldosteronism, associated with diabetic nephropathy and chronic nephritis
- Medications, such as NSAIDs and ACE inhibitors
- Addison's disease
- Inherited disorders (e.g. aldosterone synthase deficiency)
81
Pathway activated by growth hormone
JAK-STAT; mutations in this pathway can cause GH insensitivity/dwarfism
82
Inferior parathyroid glands embryological origin
Third pharyngeal pouch
83
Hypocalcemia treatment
IV calcium, oral calcitriol in acute cases. Oral calcium and cholecalciferol for maintenance.
84
Lid-lag sign of thyrotoxicosis
Result of hyperadrenergic effects. Sympathetic stimulation of Muellers muscle (superior tarsal plate).
85
For which type of pituitary adenoma is surgery NOT the primary treatment?
Prolactinoma
86
Drugs that interfere with thyroid function
Tyrosine kinase inhibitors, lithium, amiodarone, interferon-alpha
87
Iodine for treatment and particle(s)
Iodine-131 (gamma and high-energy beta)
88
Common cause of mortality in acromegaly
Cardiovascular disease (HTN, LVH, cardiomyopathy)
89
Portion of adrenal cortex that appears to be "tubular"
Zona fasciculata
90
Hyperthyroidism- treatment
Thionamides, (Methimazole, Propothiouracil) block oxidation of iodine by TPO. Propothiouracil also blocks conversion of T4 to T3. Radioiodine (I-131) can be used to ablate the thyroid.
91
Other name for toxic multinodular goiter
Plummer's disease
92
Three forms of calcium
1) free (majority)
2) protein-bound (albumin)
3) complexed to anions (least)
93
What happens to pregnenelone in the zona glomerulosa?
Converted to progesterone by 3-beta-hydroxysteroid dehydrogenase
94
Most common RET mutation in MEN2B
Methionine switched for threonine (M918T) at codon 918
95
Most important regulator of TSH levels
Free T4. Remember, most T4 is bound to thyroid-binding globulin, TBG.
96
Hashimoto's thyroiditis- ultrasound
Hypoechoic appearance
97
Follicular thyroid carinoma- presentation
Good prognosis. More common in women 40-60. Produces thyroglobulin. Hematologic spread more common, especially to bone. Requires histology for diagnosis.
98
Imaging agent taken up by any cells expressing catecholamine intake
Metaiodobenzylguanidine (MIBG)
99
Neuroblastoma cell type
Neuroblast cells (primitive sympathetic ganglion)
100
Embryological origin of the adenohypophysis
Evagination of oral ectoderm (Rathke's pouch), which regresses
101
Iodine for imaging and particle(s)
Iodine-123 (gamma)
102
Which adrenal vein is more difficult to cannulate in adrenal vein sampling?
Right side. Enters IVC directly at an acute angle.
103
Graves' disease- pathology
Follicular cells become columnar in shape. Active resorption of thyroglobulin. Infolding of epithelium. May progress to lymphocytic infiltrate and destruction of follicles, resulting in hypothyroidism.
104
What is the normal function of PTHrP
Secreted by mammary gland in lactation, mobilizing calcium for milk production.
105
How does iodine cause HYPOthyroidism?
Inadequate synthesis of T4. Compensatory TSH causes hyperplasia, resulting in a diffuse goiter.
106
Most common hormone-secreting pituitary adenoma
Prolactinoma
107
Sheehan's syndrome- pathophysiology
The adenohypophysis is enlarged during pregnancy with no additional blood supply. A superimposed peripartum hemorrhage can cause an infarction due to hypovolemic shock.
108
Mitotane
Breaks down entire adrenal cortex
109
Cortisol-cortisone shunt- mechanism
Kidneys (and colon, sweat glands, salivary glands) express 11-beta-hydroxysteroid dehydrogenase 2, which converts cortisol to cortisone (cannot activate receptor). The liver recycles cortisone back to cortisol via 11-beta-hydroxysteroid dehydrogenase 1.
110
Full name and other name for IGF-1
Insulin-like growth factor 1; somatomedin C
111
Medullary thyroid carcinoma- presentation
Neuroendocrine carcinoma of C cells. Produces calcitonin. Most are sporadic. Hereditary associated with MEN2/FMTC.
112
Follicular thyroid carcinoma- genes
Gain of function mutations that activate RAS or PI-3K/AKT arm of receptor tyrosine kinase signaling pathway. PTEN loss of function (tumor suppressor) may also occur.
113
What type of receptor is the thyroid hormone receptor (TR)? What does it do?
Nuclear receptor. When bound, it acts as a transcription factor. Increases BMR, heat production, and O2 consumption. Increases sodium-potassium pumps, which consume ATP.
114
Under what pH conditions is ionized calcium increased?
Acidosis
115
Androgen zone (adrenal)
Zona reticularis
116
What is desmopressin?
Synthetic ADH (vasopressin) with modifications to reduce the effect on vasculature and increase half-life
117
Growth hormone insensitivity treatment
Mecasermin, a recombinant IGF-1
118
What is MEN2B? (Wagemann-Froboese)
Medullary thyroid carcinoma with pheochromocytoma, mucosal neuromas, ganglioneuromas, marfanoid habitus
119
Thyroid surgery complication causing airway obstruction (inspiratory stridor)
Bilateral recurrent laryngeal nerve injury
120
Action of 5/3 monodeiodinase
Clips inner iodine molecule to make reverse T3 (inactive)
121
How do you catch a pituitary microadenoma that is not appearing on MRI?
Inferior petrosal sinus sampling
122
Thyroid surgery complication causing loss of high pitch voice/projection
Superior laryngeal nerve injury
123
Where does cortisol have negative feedback?
It has negative feedback on corticotrophs and the hypothalamus.
124
What is ergocalciferol and where do you get it?
Vitamin D2; vegetables
125
Where is RANKL synthesized?
Osteoblasts
126
M2CR ligand and function
ACTH is the ligand; stimulates glucocorticoid production
127
How does iodine cause HYPERthyroidism?
TSH increases to compensate for inadequate T4. If there is just enough iodine to "get by," it may cause some follicles to proliferate more than others to form a nodular goiter. Some nodules may become autonomous and secrete more thyroid hormone. This is a toxic multinodular goiter.
128
Blood supply to the thyroid
Superior thyroid artery (from external carotid), inferior thyroid artery (from thyrocervical trunk), thyroid ima artery (from brachiocephalic, found in 5-10% of individuals)
129
Differential diagnosis for painful and tender thyroiditis
Subacute (de Quervain's/granulomatous) thyroiditis, infections thyroiditis, radiation-induced thyroiditis, trauma-induced thyroiditis
130
What is MEN1? (Werner's syndrome)
Hyperparathyroidism (first), islet cell tumor, pituitary tumors. Caused by Menin on chromosome 11 (tumor suppressor). Autosomal dominant inheritance pattern; recessive mechanism (two-hit).
131
How do chronic granulomatous disorders cause hypercalcemia?
Activation of 1-alpha-hydroxylase
132
Neuroblastoma- median age
18 months
133
Anaplastic/undifferentiated thyroid carcinoma- genes
loss of p53 function
134
LH/FSH deficiency- presentation in men
Impotence, infertility, small testis, decreased muscle mass, reduced facial/body hair, thinning of skin (finely wrinkled)
135
What is the main function of IGF-1?
Promote organ and linear growth
136
What/where are the parvocellular neurons?
They originate in the paraventricular and arcuate nuclei of the hypothalamus and terminate in the median eminence. They secrete releasing hormones into the hypothalamic-hypophyseal portal vessels to act on the adenohypophysis.
137
Why isn't T3 helpful in hypothyroid diagnosis?
5'/3' deiodinase is upregulated to maitain T3 levels as normal
138
Pheochromocytoma- Rule of Tens
- 10% outside adrenal gland (e.g. organ of Zuckercandl)
- 10% of sporadic cases are bilateral
- 10% are malignant
- 10% do not present with HTN
139
Conn syndrome- diagnosis
Plasma aldosterone concentration (PAC), plasma renin activity(PRA);
PAC/PRA ratio of >20
May confirm with suppression tests (IV normal saline loading, fludrocortisone)
CT is good for masses. Bad for discerning unilateral vs. bilateral.
Adrenal vein sampling to determine side..
140
Superior parathyroid glands embryological origin
Fourth pharyngeal pouch
141
Compressive symptoms of goiter
Dyspnea (especially lying down), compression of recurrent laryngeal nerve, Horner's syndrome, jugular vein compression
142
Assays to diagnose growth hormone deficiency
IGF-1 and IGFBP-3 (both decreased); GH is pulsatile and not as useful clinically
143
Embryological origin of the thyroid (follicular cells)
foramen cecum of the tongue (ventral diverticulum during 4th week of gestation)
144
Hashimoto's thyroiditis antibody
Anti-TPO (diagnostic with symptoms but found in 20% of normal women). Anti-thyroglobulin may also be seen.
145
Non-metabolic effects of cortisol
Lymphocyte apoptosis, anti-inflammatory, bone health, BP regulation, CNS effects
146
17-alpha-hydroxylase is the same protein as what enzyme?
17,20-desmolase
147
Action of 5'/3' monodeiodinase
Converts T4 to more active T3
148
Name for primary hyperaldosteronism
Conn syndrome
149
What is a sestamibi scan?
Technetium is a tracer that collects in overactive parathyroid tissue
150
Waterhouse-Friderichsen syndrome
Hemorrhagic adrenalitis caused by bacteremia (e.g. Neisseria meningitidis)
151
Normal prolactin level
2-20 ng/mL
152
Pheochromocytoma- treatment
- Alpha and beta adrenergic blockade
| - Resection if possible
153
Conn syndrome- presentation
HTN, hypokalemia (1/3; may cause mild metabolic alkalosis and cramps/weakness), mild hypernatremia, higher CV mortality
154
Hyperprolactinemia- presentation
Hypogoadotropic hypogonadism, galactorrhea, infertility, amenorrhea/oligomenorrhea, impotence
155
Goiter hereditary association
MEN2A
156
ACTH rhythm and half-life (generally)
Circadian and pulsatile; highest in the morning and causes cortisol spike; short half-life
157
Papillary thyroid carcinoma- genes
Gain-of-function in growth factor receptor pathway, resulting in MAPkinase/ERK activation. RET, NTRK1 are receptor tyrosine kinases. BRAF is a serine-threonine kinase.
158
Usual order of hypopituitarism
Gonadotrophs (hypogonadotropic hypogonadism), then somatotrophs (dwarfism in children), then thyrotrophs (central hypothyroidism), and finally corticotrophs (secondary adrenal insufficiency)
159
Pituitary apoplexy- presentation
Acute onset of headache, diplopia, and hypopituitarism
160
Presentation, diagnosis, and treatment of follicular thyroid adenoma
Benign neoplasms that are usually nonfunctional but may produce thyroid hormone and cause thyrotoxicosis. Gain-of-function at TSH receptor. Suspected adenomas are removed for diagnostic lobectomy (fine needle aspiration is not useful).
161
Describe the embryological basis of the inferior parathyroid glands
Derived from third pharyngeal pouch. Descend with thymus. Reside anterior to the recurrent laryngeal nerve.
162
123-iodine scintigraphy- Graves' findings
Darker appearance, elevated uptake (50-80%), ballooning lobes, prominent isthmus, pyramidal lobe seen
163
Propothiouracil side effects
Agranulocytosis, aplastic anemia, vasculitis, hepatitis (these side effects are rare)
164
What is familial medullary thyroid carcinoma (FMTC)?
Variant of MEN2 with thyroid tumor only.Must be four or more cases in a pedigree with absece of other MEN2-associated tumors.
165
Primary sources of cholesterol (3)
1) LDL molecules via LDL-R
2) Made from acetyl-CoA
3) Esterified cholesterol stored in lipid droplets
166
SIADH- presentation
Hyponatremia with low plasma osmolality, normal/high urine osmolality, absence of hypotension or hypovolemia
167
Prolactin level with greatest concern for prolactinoma
200 ng/mL
168
Hereditary conditions associated with pheochromocytoma
- MEN2
| - von Hippel-Lindau
169
Growth hormone excess after epiphyseal plate closure
Acromegaly
170
Struma ovarii
Ovarian teratoma with mature thyroid tissue that secretes hormone
171
Normal calcium level
8.5-10.5 mg/dL
172
Darkest/most basophilic part of adrenal cortex on histology
Zona reticularis
173
Hypoaldosteronism- presentation
Metabolic acidosis with normal anion gap; typically not associated with sodium wasting. AKA type IV renal tubular acidosis.
174
Where are most craniopharyngiomas found?
Most from the pituitary stalk, with a minority found in the intrasellar space.
175
Embryological origin of parafollicular (C) cells
Ultimobranchial body (part of fourth pharyngeal pouch)
176
Papillary thyroid carcinoma- pathology
Psammoma bodies are microcalcifications (visible on ultrasound). Orphan-Annie nuclei have a ground glass apearance. Intranuclear grooves.
177
Follicular thyroid carcinoma- pathology
Tightly packed, small follicles with scant colloid. Occasional cells with abundant granular eosinophilic cytoplasm (Hurthle cell variant).
178
Hypoaldosteronism- treatment
Fludrocortisone
179
Some somatotrophs are also what type of cell?
Lactotrophs
180
Cushing syndrome presentation
moonface, dorsocervical fat bad, central obesity, etc.
181
Cretinism- cause
Hypothyroidism during fetal development. Supplementation may improve stature but not mental deficits.
182
Calcitonin function
Inhibits bone resorption of bone in times of stress on skeleton. May inhibit renal calcium absorption. In normal adults, little effect on serum calcium. Strong effect when bone turnover is increased (thyrotoxicosis, Paget's)
183
Graves' disease- antibody
TSH receptor antibody (TRAB), which agonizes receptor and does not let go
184
Enzyme that converts testosterone to DHT
5-alpha-reductase
185
Cortisol-cortisone shunt- purpose
Prevents large volume of cortisol from activating mineralocorticoid receptor
186
Time course of thyroiditis and treatment
Initially, leakage of stored thyroid hormone from colloid causes a 3-8 thyrotoxic phase, with a euthyroid phase as levels decline. The hypothyroid phase is usually asymptomatic. Recovery usually happens at 5-6 months. Beta-blockers for symptom relief.
187
SIADH- treatment
Fluid restriction, high solute intake/IV saline
188
Ghrelin promotes the secretion of which pituitary hormone?
Growth Hormone (synergistic with GHRH)
189
Papillary thyroid carcinoma- presentation
Best prognosis. Usually in individuals age 25-50, often with exposure to ionizing radiation. Produces thyroglobulin. Commonly spreads to lymphatics/nodes. Hypoechoic on ultrasound, and may show calcifications.
190
Enzyme that changes steroid from mineralocorticoid path to glucocorticoid path
17-alpha-hydroxylase
191
Central diabetes insipidus- treatment
Desmopressin
192
In what disease is a RET loss-of-function mutation observed?
Hirschsprung disease
193
Adrenal insufficiency- presentation
Weakness, fatigue, muscle/joint pain, hhponatremia, hypoglycemia, hyperpigmentation (sun exposed areas, due to increased ACTH and aMSH)
194
Craniopharyngioma- presentation
Headache, visual impairment, hormonal deficiency (growth failure)
195
Number of carbons in cholesterol
27
196
Pro-opiomelanocortin (POMC) cleavage products
ACTH and alpha-melanocyte stimulatinghormone (aMSH)
197
Treatment of hypercalcemia
Bisphosphonates (antiresorptive), cinacalcet (calimimetic). AVOID thiazides, lithium. In severe cases, saline loading, denosumab (RANKL inhibitor)
198
Name for hypersecretion of vasopressin
Syndrome of Inappropriate ADH (SIADH)
199
Cushing syndrome diagnosis
Overnight dexamethasone suppression test (fail to suppress cortisol), high midnight salivary cortisol, 24-hour urinary free cortisol, metyrapone test, ACTH levels
200
What is Laron Dwarfism?
Growth hormone insensitivity due to a mutation in the GH receptor
201
Empty sella (primary)- pathophysiology
Defect in the diaphragma sella allows CSF through, compressing the pituitary gland and enlarging the sella over time. Usually an asymptomatic, incidental finding.
202
Chief cell function in parathyroid glands
Synthesize, store, and secreate PTH
203
What are clinical tests for hypocalcemia?
Chvostek's sign, Trousseau's sign
204
Neuroblastoma- diagnosis
Elevated urine levels of catecholamines, metanephrines, homovanillic acid, VMA
205
Cortisol rhythm and half-life
Highest in the morning; long half-life
206
Order of enzyme actions in the zona glomerulosa
1) Cholesterol => prenenolone by cholesterol desmolase
2) Pregnenolone => progesterone by 3-beta-hydroxysteroid dehydrogenase
3) Progesterone => 11-deoxycortisone by 21-hydroxylase
4) 11-deoxycortisone-corticosterone by 11-beta-hydroxylase
5) Corticosterone => aldosterone by aldosterone synthase
207
Role of M3CR and M4CR
Appetite suppression; M4CR suppressed by agouti-related peptide (ghrelin pathway)
208
Oxyphil cell function in parathyroid glands
Who knows?
209
123-iodine scintigraphy- subacute/silent thyroiditis findings
Diffusely suppressed, may be patchy, uptake is very low
210
Causes of hyperprolactinemia
- Pregnancy
- Nipple stimulation
- Physical activity/stress
- Pituitary adenoma
- Hypothyroidism
- Exogenous estrogens
- Interfering with dopamine inhibition of lactotrophs
211
Where are calcium and magnesium passively reabsorbed between cells?
Thick ascending limb of the loop of Henle
212
Adrenal cortical adenoma- pathophysiology
Benign neoplasm of adenocortical cells that can secrete steroids independently of ACTH or RAS pathway
213
Glucocorticoid zone
Zona fasciculata
