Parathyroid Flashcards
(160 cards)
1
Q
Which embryological tissue does the thyroid come from?
A
Endoderm
2
Q
What are the 2 thyroid hormones from the folliclar (principle) cells?
A
T3 and T4
3
Q
Which organelle is numerous in the follicular cells?
A
RER
4
Q
What are the colloidal resorption droplets in the follicular cells of the thyroid?
A
lysosomes and endocytotic vesicels
5
Q
What are the cells in the periphery of the follicular epithelim and secrete calcitonin?
A
Parafollicular (C) cells
6
Q
What do u see in the C cells of the thyroid?
A
small secretory veiscles and a prominent golgi apparatus
7
Q
Which branchial pouches are the parathyroid from?
A
3rd and 4th
8
Q
Which embryological tissue does the parathyroid come from?
A
endoderm
9
Q
What is the H that the principle cells secrete from the parathyroid?
A
PTH
10
Q
What are the other parathyroid cells, which are larger than principle and are strongly acidophilic?
A
Oxyphil cells
11
Q
What is the gross anatomy of the thyroid?
A
2 lateral lobes and an isthmus that connects the anterior surface
12
Q
Which CN is closely realted to the thyroid?
A
recurrent laryngeeal nerves of X
13
Q
What do the superior/inferior thyroid aa come from?
A
Superior thyroid - ECA
Inferior thyroid- from thyrocervical trunk
14
Q
Which random a. is at risk for dmg in a tracheostomy?
A
Thyroid ima a.
15
Q
Which pharyngeal pouches make the 2 upper and 2 lower parathryoid glands?
A
2 superior- 4th puch
2 inferior- 3rd pouch
16
Q
What is the duct that is at the back of the tongue that is a remnant of the descent of the thyroid?
A
Thyroglossal duct
17
Q
What is the result if the 2nd pharyngeal arch fails to grow over the 3rd and 4th arches?
A
Branchial fistula
18
Q
What is the hump on the side of the neck called form a fistula?
A
Lateral cervical cyst
19
Q
What is it called when there is an opening to the anterior neck from a fistula?
A
External branchial fistula
20
Q
Where does the internal brancial fistula travel?
A
To the palatine tonsils
21
Q
What is it called when there is persistant remnants of the pharyngeal cartilage or bony elements?
A
Branchial vestiges
22
Q
Where is the typical location for brancial vestiges?
A
anterior to the inferior 1/3 of the SCM
23
Q
What is it called when the thyroid doesnt descend correctly from the oral cavity to the neck?
A
Ectopic thyroid tissue
24
Q
What might occur in the thyroglossal duct from the foramen cecum to the thyroid on the neck?
A
Cysts
25
What are the Sx of DiGeorge syndrome?
```
Cleft palate
Abnormal facies
Thyroid atresia
Cardial abnormalities
Hypocalcemia
22q11 deletion
```
"CATCH 22"
26
What % of Ca in the body is ionized? bound? complexed to anions?
Ionized 50%
Bound 41%
Complexed 9%
27
What is the nromal rate of Ca intake?
1g/day
28
How much Ca is lost in the feces and urine per day?
900mg in the poop
| 100mg in the urine
29
What is the role of Ca on Na which causes neurvous excitement and tetany?
Ca inhibits the permeability of neurons --> low Ca --> ↑ membrane permeability to Na --> easy AP's
30
What level do Ca ions drop to in hypocalcemia to cause tetany from normal (9.4mg/dl)?
6 mg/dl
31
What happens to the EKG, appetite, and GI in hypercalcemia?
↓ QT interval
↓ appetite
Constipation
32
At what mg/dl do u see Ca crystals in the body?
> 17 mg/dl
33
What makes up 90-95% of the organic matrix of the bone?
collagen fibers
34
What makes up the remaining 10% of the bone?
Ground substance (proteoglycans, like chondroitin sulfate and hyaluronic acid)
35
What are the cells for bone production?
Osteoblasts
36
What do osteoblasts secrete to build bone?
collagen and gorund substance
37
What do osteoblasts secrete, which is a cytokine, that inhibits bone resorption?
OPG
38
What are the cells for bone resorption?
Osteoclasts
39
What do osteoclasts secrete to eat bone?
Proteolytic enzymes and acids (citric acid and lactic acid)
40
Give me the whole vitamin D synthesis pathway
Sun makes cholecalciferol (D3) --liver--> 25-hydroxycholecalciferol --kidney--> 1,25 dihydrocholecalciferol
41
What are the 3 increases of 1,25 dihydrocholecalciferol?
↑ Ca-binding protein
↑ Ca-stimulated ATPase
↑ Alkaline phosphatase
42
What enzyme does PTH stimulate in the kidney to increase Ca levels in the blood?
1-a-hydroxylase
| makes 1,25 dihydrocholecalciferol
43
What suppresses PTH levels?
Ca++
44
What molecule does 1,25 dihydrocholecalciferol cause increased formation of in the GI?
Calbindin
45
What is the role of calbindin in the GI?
helps transport Ca into the cell cytoplasm
46
What other molecule is enhanced by 1,25 dihydrocholecalciferol to be absorbed in the GI?
Phosphate
47
What is the role of 1,25 dihydrocholecalciferol on the nephrons?
Increases Ca and phosphate reabsorption
48
What happens to bone in the presence of 1,25 dihydrocholecalciferol?
↑ absorption
49
Again, which cells of the parathyroid make PTH?
Chief cells
50
Generally, what happens to serum Ca and phosphate under the control of PTH?
Ca ↑
| Phosphate ↓
51
This is the rapid phase of bone resorption from PTH, where there is activation of osteocytes to promote Ca and phosphate salt resorption.
Osteolysis
52
Which bone cell does PTH bind to, which stimulates osteolysis?
PTH receptor is on osteoBLASTS, which stimulate osteoCLASTS to eat bone.
53
PTH causes the loss of what substance form the kidney?
Phosphate
54
What is the role of PTH on the kidney for Ca?
↑ renal tubular reabsorption
55
WHERE in the nephron does PTH act to ↑ Ca reabsorption?
PCT + DCT + CD
56
What condition in kids has an increased PTH, which makes them have bad bones?
Rickets (↓ vit D)
57
What female condition can make u have high PTH in the blood?
Pregnancy + lactation
| Ca is used for breast milk
58
What is the R in the parathryoid membranes that detects changes in [Ca]?
Calcium-sensing receptor (CaSR)
59
Once the CaSR is stimulated by Ca, what pathway does it use to ↓ PTH release?
Gq pathway, which causes the relase of Ca from intracellular stores and in turn ↓ PTH release
60
What is the H that antagonizes PTH, which ↓ plasma Ca?
Calcitonin
61
What is the stimulus for Calcitonin release?
↑ Ca++
62
In addition to shutting down osteoclasts, what does calcitonin do in kids to save the bone from the evil PTH?
↑ bone remodeling
63
What are the 2 reasons calcitonin doesnt have that big of an effect on adults?
1. any ↓ in serum Ca causes a PTH spike
| 2. daily Ca intake/use is small
64
this is the condition where there is inappropriate, excess PTH secretion --> high Ca, low phosphate levels.
Primary hyperparathyroidism (HPT)
65
What is the most common cuase of primary HPT?
tumor of the parathyroid gland
66
What are the main problems with primary HPT?
Fractures + osteoitis fibrosa cystica
67
What are the Alkaline phosphatase levels in primary HPT?
HIGH alkaline phosphatase
68
What do we mean by "stones, bones, andominal groans, psychiatric overtones" in primary HPT?
Kidney stones
Bone Fx
Constipation/PUD/↓ appetite
↓ CNS/PNS
69
What is the cuase of secondary HPT?
a compensation for hypocalcemia
70
Disease of what organ can cause secondary HPT?
Chronic renal disease
| no 1,25 dihydrocholecalciferol
71
What is the main cause of lack of vitamin D?
Living in Erie
72
What are the Ca levels in the blood in rickets?
Low
73
The Ca levels in the blood are low in rickets, but what ion level is extremely low in the blood?
Phosphate
| low Ca --> ↑ PTH release --> ↑ excretion of phosphate
74
The lack of physical stress on bones from a lack of activity (sitting on yer ass and studying all day) can lead to what problem?
Osteoporosis
75
The lack of what vitamin can cause osteoporosis cuz osteoid can't form corectly?
Vitamin C
76
What is the relationship between estrogen and osteoclasts?
Estrogen ↓ osteoclasts
| this is why postmenopausal women, who dont make estrogen, are at risk for osteoporosis
77
Which cell activity decreases in Cushings?
Osteoblasts
78
What FORM of Ca does PTH regulate from the chief cells?
Free (ionized) Ca++
79
What is the most common cause of primary HPT?
Parathyroid adenoma (>80%)
80
What forms in the kidney in primary HPT?
Ca oxalate stones
81
This is a complication of primary HPT where there is metastatic calification of renal tubules, potentially leading to renal insufficicency and polyuria.
Nephrocalcinosis
82
Since Ca can activate enzymes, what GI problem can people with primary HPT have?
acute pancreatitis
83
What are the changes to the following labs in primary HPT?
```
Serum PTH
Serum Ca++
Serum Phosphate
Urinary cAMP
Serum Alkaline phosphate
```
```
Serum PTH ↑
Serum Ca++ ↑
Serum Phosphate ↓
Urinary cAMP ↑
Serum Alkaline phosphate ↑
```
84
Which cells cause the ↑ serum alkaline phosphate, as a result of primary HPT?
Osteoblasts
(remember these are activated by PTH --> release ALKP to make bone in addition to activation of osteoclasts --> ↑ serum levels in primary HPT)
85
What is the treatment for primary HPT?
CUT IT OUT
86
What is the most common cause of secondary HPT?
renal insufficiency
87
Renal insufficiency in secondary HPT causes the ↓ exretion of which ion?
Phosphate
88
the ↓ excretion of Phospahte in secondary HPT causes what change in serum Ca?
serum Ca ↓
| because the ↑ serum phosphate binds to it
89
And when the ↑ serum phosphate binds to Ca, and serum Ca levels ↓, what is released as a response?
PTH
90
So what happens to the following lab values in secondary HPT?
Serum PTH
Serum Ca++
Serum Phosphate
Serum Alkaline phosphate
Serum PTH ↑
Serum Ca++ ↓
Serum Phosphate ↑
Serum Alkaline phosphate ↑
91
What are the 3 main causes of hypoparathyroidism?
Autoimmune dmg to parathyroids (hashimotos), surgical excision, and DiGeorge syndrome
92
The low serum Ca in hypoparathyroidism causes what sensory problems?
Numbness and tingling (esp around the lips)
93
This is a sign of hypoparathyroidism where there is tetany from filling up a blood pressure cuff.
Troussau sign
94
This is a sign of hypoparathyroidism where there is tetany from tapping on the facial n.
Chvostek stign
95
What happens to PTH in pseudohypoparathyroidism?
↑ resistance to PTH
| ↓ Gs stimulatory protein
96
What are the serum levels of Ca and PTH in pseudohypoparathyroidism?
↓ Ca
| ↑ PTH
97
The AD form of pseudohypoparathyroidism causes what anatomical defects?
Short stature
| short 4th and 5th fingers
98
PTH, shear stress, and TGF=B cause osteoblast precursors to express which osteoclast ligand?
RANK-L
99
The RANK-L on the osteoblast precursor stimulate which other precursor (which has the RANK)?
osteoclast precursor
100
What is the molecule released that causes the osteoclast precursors to differentiate into mature osteoclasts?
M-CSF
| with stimulation by RANK
101
What is the drug that acts on CaSR, act causes them to activate at lower concentrations?
Cinacalcet
102
What are the drugs that lower plasma phosphate by preventing dietary phosphate absorption?
Phosphate binders
103
What are the 3 ways that estogen treatment leads to slow bone resorption?
Reduces cytokines that induce osteoclasts
Promotes apoptosis of osteoclasts
Inhibits apoptosis of osteoblasts and osteocytes
104
Though estrogen HRT benefits bones, what are the 2 risks of its use?
Cardiovascular disease
| Breast CA
105
What is the estrogen agonist in bone bu estrogen antagonist in the endometrium and breast?
Raloxifene
106
Since raloxifene stimualtes only the bone, what does it bypass the risk in estrogen HRT?
Cardiovascular disease
| Breast CA
107
What does raloxifine do to LDL levels?
Lowers them (helps prevent heart disease)
108
What is the downside to raloxifine?
Still increases risk of venous thromboembolism
109
What is the suffix to all bisphosphonates except zoledronic acid?
-dronate
110
Where do bisphosphonates accumulate?
Bone
111
What do bisphosphonates do in the bone treat osteoporosis, hypercalcemia of malignancy, and Paget's?
osteoclast apoptosis
112
What is the general indication for pamidronate and zoledronate?
hypercalemia of malignancy
113
What are the 2 contraindication to pamidronate and zoledronate?
dental disease and oral surgery
114
What is the indication for oral aledronate/risedronate?
Osteopenia/porosis
115
Bisphosphonates decrease the risk of what fractures?
Vertebral
116
Why are bisphosphonates taken orally in the morning on an empty stomach?
low oral bioavailability
117
What is the monoclonal Ab against the RANK-L?
Denosumab
118
What does calcitonin bind and activate on osteoclasts to decrease their resorptive activity?
G-protein R
119
What are the 3 indications for calcitonin?
Pagets
Osteoporosis
hyperCa
120
Antiresorptive agents are not helpful in which pts?
Thos who have already lost a large amt of bone mass (BMD > SD's below normal)
121
What makes PTH (1-34) different than normal PTH to increase bone remodeling with more new bone formed than old resorbed?
It causes intermittent stimulation of bone cells
122
What do calcium carbonate, calcium acetate, and sevelamer do to dietary phosphate?
Bind it and inhibit its absorption?
123
What are the 3 vitamin D congeners that bypass the need for 1-a-hydroxylation in the kidney?
Calitrol (1,25(OH)2D3)
Paricalcitrol (19-nor-1,25(OH)2D2)
Doxecalciferol (1a-(OH)D2)
124
What drugs can modulate activity of Ca2+-sensing receptors in chief cells such that they can treat hyperparathyroidism without causing unwanted hypercalcemia & hyperphosphatemia?
Calcimimetrics
125
What is the calcimimetric that binds to the transmembrane region of the CaSR and activates it at lower Ca++ concentrations, thus ↓ PTH?
Cinacalcet
126
What are the 2 indicaitons for Cinacalcet?
secondary HPT
| hyperCa with parathyroid carcinoma
127
What population can benefit from Ca supplements, which reduce vertebral bone loss?
Postmenopausal women
128
What is the treatment for Viramin D resistant rickets + hypophosphatemia?
Oral phosphate and high doses of vit D
Calcitriol is good too
129
What is the treatment for type I vitamin D-dependent rickets?
Vitamin D or calcitrol
130
What is the treatment for type II vitamin D-dependent rickets?
High dose calcitrol
131
What is the most common cause of hypercalcemia in ambulatory pts?
Primary HPT
132
What happens to the parathyroids in familial primary HPT?
Hyperplasia of the parathyroids
133
What is the treatment of choice for primary HPT?
CUT IT OUT
134
What is the electrolyte abnormality after a surgical parathyroidectomy?
Reversible, mild, asymptomatic hypocalcemia
135
This is the cause of hypercalcemia from either destructive effects of malignancy or the paraneoplastic effect of malignancy?
Hypercalcemia of malignancy
136
What is the serum PTH levels in hypercalcemia of malignancy?
low serum PTH
| paraneoplastic syndromes can secrete PTHrp which can cause hypercalcemia --> low PTH
137
This is the cause of hypercalcemia where there is also hypercalciuria, renal insufficiency, and soft tissue calcification.
Vitamin D intoxication
138
What enzyme do some lymphomas have to cause hypercalcemia?
1a-hydroxylase
139
Hypercalcemia and granulomatous disorders are indications for what treatment?
Glucocorticoids
140
What is the type of surgery which may damage the parathryoid glands and cause hypoparathyroidism?
Thyroidectomy
141
What is the electrolyte abnormality which impairs secretion of PTH?
Hypomagnesemia
142
This is the condition where there is end-organ resistance to the actions of PTH beceause of a receptor or postreceptor defect.
Pseudohypoparathyroidism
143
What is the variant of Pseudohypoparathyroidism where the patients have the same characteristic physical features but not the biochemical abnormalities?
Pseudopseudohypoparathyroidism
Did you know that this condition (at 30 letters) is the second longest medical word in the dictionary? It’s second to Pneumonoultramicroscopicsilicovolcanoconiosis, which has 45 letters.
144
What is the EKG abnormality in hypocalcemia?
prolonged QT
145
What binds to Ca in the blood?
Albumin
146
What is the diagnostic test of hypoparathyroidism in a hypocalemic pt?
Serum PTH
(hypoparathyroidism with hypocalcemia cuases a low PTH
147
What is the treatment for severe acute hypocalcemia which prevents tetany, stridor, or convulsions?
Rapid IV Calcium gluconate
148
This is when u have a bone mass > 2.5 SD's below the peak bone mass of a sex and height-matched control population?
Osteoporosis
149
This is when u have a bone mass 1-2.5 SD's below the peak bone mass of a sex and height-matched control population?
Osteopenia
150
What are the 4 endocrine disorders that can cause osteoporosis?
Hypogonadism
HPT
Hyperthyroidism
Hypercortisolism
151
What are the common sites for osteoporotic fractures?
Vertebrae, Hip, distal Radius
152
What are the serum levels of Ca, phosphate, and alkaline phosphatase in osteoporosis?
Normal
153
What is the test that can be used to assess bone mineral density of the lumbar vertebrae?
Dual energy x-ray absorptiometry
154
Diffuse bone pain and tenderness, muscle weakness, and waddling gait are indications for what bone problem?
Osteomalacia
155
What are the 3 effective therapies for osteomalacia?
Calcium
Vitamin D
Phosphate (when indicated)
156
This is a monostotic or polyostotic bone disorder characterized by the presence of abnormal osteoclasts, which lead to an increased rate of bone resorption and, subsequently, disorganized bone remodeling.
Paget disease
157
Which blood test is elevated in Paget disease?
Serum alkaline phosphate
158
What are the 3 bones commonly affected by Paget?
Long bones, skull, or spine
159
What are the serum levels of calcium, phosphate, and 25-hydroxyvitamin D in Paget?
Normal
160
What is the category of drugs used in the medical therapy of Paget?
IV Bisphosphonates
