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CP3 Medicine > ENDOCRINE - Calcium And Vit D > Flashcards

ENDOCRINE - Calcium And Vit D Flashcards

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1
Q

Why is 40% of plasma calcium inactive?

A

Because it is bound to albumin

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2
Q

If someone has low albumin, how will their non-adjusted calcium appear?

A

Low

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3
Q

Effect on acidotic states on ionized Ca2+ ( why)

A

Increase Ca2+

By decreasing albumin binding

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4
Q

Effect on alkalotic states on Ca2+ (ionized) + why

A

Decreased ionized Ca2+

By increasing albumin binding

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5
Q

WHere are the Parathyroid glands

A

Lying posterior to the thyroid

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6
Q

Which cells secrete Parathyroid hormone (PTH)

A

Chief cells

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7
Q

When is PTH secreted (3)

A

When plasma Ca = low
If Vit D = low
If PO4 = high

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8
Q

3 ways in which PTH increases plasma Ca levels

A

Directly stimulating Ca reabsorption from bone
Directly increasing renal tubular Ca reabsorption
Indirectly stim incr GI Ca absorption (by incr Vit D activation kidney)

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9
Q

Secondary effect of PTH

A

Increases renal PO4 excretion

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10
Q

Affect of Vit D on Ca + PO4 levels

A

Sustains/increases both by increasing inflow from GIT

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11
Q

How is Vit D synthesised endogenously

A

In kin —> D3 (cholecalciferol)

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12
Q

How is Vit D ingested exogenously

A

As D2 - ergocalciferol

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13
Q

Where does 1st hydroxylation of Vit D take place

A

Liver

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14
Q

Where does 2nd hydroxylation of Vit D take place

A

Kidneys = active form

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15
Q

Where is calcitonin secreted

A

Parafollicular C cells of thyroid gland

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16
Q

What is Calcitonin secreted in response to

A

High levels of Ca

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17
Q

How does Calcitonin decrease Ca

A

Antagonism of effect of PTH on bone

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18
Q

What is 90% of renal excretion of Ca related to

A

Sodium reabsorption PCT

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19
Q

What is the other 10% of Ca renal excretion related to

A

PTH regulation in the distal tubule

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20
Q

WHat is 97% of hypercalcaemia due to?

A

1’ hyperPTH or malignancy

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21
Q

Distinguishing 1’hyperPTH from malignancy

A

PTH high in 1’hyperPTH

PTH low In malignancy + Ca much higher

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22
Q

Causes of hypercalcaemia

A

XS PTH secretion - 1/3’hyperPTH + ectopic PTH secretion
Myeloma
Mets deposits in bone
Paraneoplastic - PTHrp (SCC)/Production of osteoclasts factors
XS Vit D - exogenous, TB/Sarcoid/ lymphoma
Milk-alkali syndrome
Thyrotoxicosis
Addisons
Severe AKI
Sx - thiazides diuretics, Li
Familial hypocalcicuric hypercalcaemia

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23
Q

What is 80% of 1’hyperPTH due to

A

Parathyroid adenomas

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24
Q

What are the other 20% of 1’hyperPTH due to?

A

Diffuse hyperplasia of all glands (e.g. as part of MEN1/2a)

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25
PTH and Ca2+ levels 1’hyperPTH
Ca2+ + PTH high
26
Tx 1’hyperPTH
Parathyroidectomy
27
Is parathyroidectomy indicated in asymptomatic 1’hyperPTH
YES | Because of potential LT adverse effects
28
After parathyroidectomy, how long does it take for ca2+ to be norm again
24hrs
29
Complication parathyroidectomy + how. To prevent it
Hypocalcaemia | Give 14 days AdCal post op
30
What is 2’hyperPTH
Physiological hypertrophy of all PT glands due to hypocalcaemia
31
Which conditions can cause 2’hyperPTH (2)
Renal disease | Vit D deficiency
32
2’hyperPTH - Ca + PTH levels
PTH high | Ca low/norm
33
Tx 2’hyperPTH
Tx cause
34
What is 3’hyperPTH due to
Long standing 2’ hyperPTH esp in renal failure
35
Ca/PO4/PTH levels 3’hyperPTH
Ca high PTH high PO4 very high q
36
Tx 3’hyperPTH
Parathyroidectomy
37
Sx 1’hyperPTH (5)
``` Usually asymp. If Sx: BONES STONES ABDO GROANS PSYCHIC MOANS ```
38
Bone Sx 1’hyperPTH (3)
Bone pain Pathological fractures Mm weakness
39
Stone Sx 1’hyperPTH
Renal stones Polyuria AKI/CKD
40
Abdo groans Sx 1’hyperPTH (5)
``` Abdo pain Vomiting Constipation Pancreatitis GI ulcers ```
41
Psychic moans Sx 1’hyperPTH/hyperCa (4)
Depression Confusion Tiredness Hypotonicity
42
ECG changes 1’hyperPTH/hypercalcaemia
Reduced QT interval —> cardiac arrest
43
Ix 1’hyperPTH (8)
``` PTH raised Ca raised PO4 reduced ALP raised 24 urinary Ca raised DXA scan - extent of OP Technetium scan - tumour localisation USS - tumour localisation ```
44
Why do we do 24h urinary Ca in Ix 1’hyperPTH
To rule out familial hypocalciuric hyerpcalcaemia
45
Classical XR changes 1’hyperPTH
Hand XR - classic subperiosteal bone resorption
46
Men 1 - 3 Ps
Parathyroid hyperplasia/adenoma Pancreatic endocrine tumours - gastronomy/insulinoma Pituitary adenoma
47
Men 2a - TAP
Thyroid - medullary carcinoma Adrenal PCC Parathyroid hyperplasia
48
Men 2b
MEN2+ mucosal neuromas + Marfanoid appearance | No hyperPTH
49
When to Tx hypercalcaemia
If >3.5 + severe Sx
50
Tx hypercalcaemia
3-6L 0.9% NaCl over 24h | Disphosphonates - 1 dose pamidronate
51
When to use calcitonin in Mx hypercalcaemia
Life threatening hypercalcaemia as rapidly reduces Ca
52
When to use dialysis in Mx hypercalcaemia
If renal impairment
53
When to use steroids in mx hypercalcaemia
If hypercalcaemia = due to myeloma, lymphoma or sarcoid
54
When may hypocalcaemia be an artefact?
If low serum albumin is not corrected
55
Causes of hypocalcaemia w/ low PTH (DiGeorge says HIIIII)
``` Digeorge syndrome Severe Hypomagnesia Idiopathic (1'hypoPTH) autoImmune Iatrogenic - post thyroid/parathyroid surgery post neck Irradiation Infiltration - sarcoid/malignancy ```
56
Causes of hypocalcaemia w/ high PTH
``` Dick and Vagina always relieve Robs anal tension Dx - bisphosphonates/calcitonin Acute Hyperphosphataemia Vit D defcieincy Alkalosis Renal failure Rhabdomyolysis Acute pancreatitis Tumour lysis ```
57
S+S hypocalcaemia (10)
``` Peripheral irritability Tetany/cramps Trosseau's sign Chvostek's sign Central irritability Seizures Depression/anxiety Perioral parasethesia Cataracts ```
58
What is Trosseau's sign
Wrist flexion + fingers drawn together Esp after occlusion of brachial aa ie BP cuff Hypocalcaemia
59
What is Chvostek's sign
Tapping over facial nn causes twitches | Hypocalcaemia
60
Ix hypocalcaemia (5)
``` Se Ca = low Se PTH = low or high Check Parathyriod ab if low Se Vit D ECG - prolonged QT ```
61
Mx mild-mod hypocalcaemia
AdCal
62
Mx severe hypocalcaemia (2)
Ca gluconate IV 10ml 10% bolus then maintenance infusion | AdCal ASAP

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