Calcium and Parathyroid Hormone

Question 1

What are the actions of PTH?

Answer 1

Ca2+ reabsorption
Bone resorption
Indirect Ca2+ absorption (increased 1,25 (OH)2 vit D

Question 2

Is it hypocalcaemia if low serum albumin, low total serum calcium but not a low ionised calcium?

Answer 2

No

Question 3

What is the equation for working out corrected calcium?

Answer 3

total serum calcium + 0.02 * (40 – serum albumin)

Question 4

What are consequences of hypocalcaemia?

Answer 4

• Parasthesia
• Muscle spasm
  
  • Hands and feet
  • Larynx
  • Premature labour
• Seizures
• Basal ganglia calcification
• Cataracts
• ECG abnormalities
  
  • Long QT interval

Question 5

What is Chvostek’s Sign?

Answer 5

• Tap over the facial nerve
• Look for spasm of facial muscles

Question 6

What is Trousseau’s Sign?

Answer 6

• Inflate the blood pressure cuff to 20 mm Hg above systolic for 5 minutes
• Hand forms shape

Question 7

What could cause hypocalcaemia?

Answer 7

Vit D deficiency

Question 8

What will the levels of PTH be like in vit D deficiency (secondary hyperparathyroidism)?

Answer 8

High

Question 9

What will the levels of calcium be like in vit D deficiency (secondary hyperparathyroidism)?

Answer 9

Low

Question 10

What will the levels of phosphate be like in vit D deficiency (secondary hyperparathyroidism)?

Answer 10

Low

Question 11

Is the action of PTH appropriate or inappropriate in vit D deficiency (secondary hyperparathyroidism)?

Answer 11

Appropriate
- In attempt to raise calcium
- Increased phosphate excretion in kidney

Question 12

What can cause hypoparathyroidism?

Answer 12

• Surgery
• Radiation
• Syndromes
• Developmental abnormality of third and fourth branchial pouches
• Genetic
• Autoimmune
• Infiltration
• Magnesium deficiency

Question 13

How can surgery cause hypoparathyroidism?

Answer 13

• neck surgery can cause parathyroid to be damage
• Commonest cause

Question 14

Which is the most common syndrome to cause hypoparathyroidism?

Answer 14

Di George

Question 15

What will the levels of PTH be like in hypoparathyroidism?

Answer 15

Low

Question 16

What will the levels of calcium be like in hypoparathyroidism?

Answer 16

Low

Question 17

What will the levels of phosphate be like in hypoparathyroidism?

Answer 17

High

Question 18

Is the action of PTH appropriate or inappropriate in hypoparathyroidism?

Answer 18

Inappropriate

Question 19

What is psuedohypoparathyroidism?

Answer 19

• Resistance to parathyroid hormone
  
  • Receptors on organs don’t respond to PTH
  • Inherited
  • Type 1 Albright hereditary osteodystrophy
    
    • caused by mutation with deficient Gα subunit

Question 20

What are the signs of pseudohypoparathyroidism?

Answer 20

• Short stature
• Obesity
• Round facies
• Mild learning difficulties
• Subcutaneous ossification
• Short fourth metacarpals
• Other hormone resistance

Question 21

What will the levels of PTH be like in pseudohypoparathyroidism (PTH resistance)?

Answer 21

High

Question 22

What will the levels of calcium be like in pseudohypoparathyroidism (PTH resistance)?

Answer 22

Low

Question 23

What will the levels of phosphate be like in pseudohypoparathyroidism (PTH resistance)?

Answer 23

High

Question 24

Is the action of PTH appropriate or inappropriate in pseudohypoparathyroidism (PTH resistance)?

Answer 24

Appropriate
- PTH acting normally, receptors resistant

Question 25

What may look like hypercalcaemia actually be instead?

Answer 25

• Tourniquet on for too long
• Sample old and haemolysed

Question 26

What are symptoms of hypercalcaemia?

Answer 26

• Thirst, polyuria
  
  • Excess Ca
• Nausea
  
  • Gut is a muscle, gut stasis
• Constipation
• Confusion → coma

Question 27

What could chronic hypercalcaemia lead to?

Answer 27

• Renal stones
• ECG abnormalities
  
  • Short QT

Question 28

What is 90% of hypercalcaemia caused by?

Answer 28

• Malignancy
  
  • bone mets, myeloma, some
    tumours produce PTHrP,
    lymphoma
  • PTHrP acts like PTH
  • Lymphomas can activate
    vitamin D
• Primary hyperparathyroidism

Question 29

What is 10% of hypercalcaemia caused by?

Answer 29

• Thiazides
• Thyrotoxocosis
• Sarcoidosis
• Familial hypocalciuric / benign hypercalcaemia
• Immobilisation
  
  • Bone resorption
• Milk-alkali
  
  • Usually in people with renal impairment
• Adrenal insufficiency
• Phaeochromocytoma

Question 30

What will the levels of PTH be like in hypercalcaemia of malignancy?

Answer 30

Low

Question 31

What will the levels of calcium be like in hypercalcaemia of malignancy?

Answer 31

High

Question 32

What will the levels of phosphate be like in hypercalcaemia of malignancy?

Answer 32

Depends

Question 33

Is the action of PTH appropriate or inappropriate in hypercalcaemia of malignancy?

Answer 33

Appropriate

Question 34

What are consequences of Primary Hyperparathyroidism?

Answer 34

• Bones
  
  • Osteitis fibrosa cystica
  • Osteoporosis
• Kidney stones
• Psychic groans
  
  • confusion
• Abdominal moans
  
  • Constipation
  • Acute pancreatitis

Question 35

What is 80% of Primary Hyperparathyroidism due to?

Answer 35

single benign adenoma
- can be treated by minimally invasive parathydroidectomy

Question 36

What is 15-20% of Primary Hyperparathyroidism due to?

Answer 36

• four gland hyperplasia
  
  • All 4 glands overgrowing
  • may be part of MEN I or II

Question 37

What is <0.5% of Primary Hyperparathyroidism due to?

Answer 37

malignant

Question 38

What will the levels of PTH be like in Primary hyperparathyroidism?

Answer 38

High

Question 39

What will the levels of calcium be like in Primary hyperparathyroidism?

Answer 39

High

Question 40

What will the levels of phosphate be like in Primary hyperparathyroidism?

Answer 40

Low

Question 41

Is the action of PTH appropriate or inappropriate in Primary hyperparathyroidism?

Answer 41

Inappropriate