Hyper and hypocalcaemia Flashcards

1
Q

Parathyroid anatomy
- Size
- Location, including neighbouring structures
- VAN

A

4 parathyroid glands
- Size of rice grain (roughly 6mm long)

Location
- Posterior to thyroid, two superior and two inferior.

V- Superior, middle and inferior thyroid.
Sup + middle- drains into IJV
Inferior drains into Brachiocephalic

A- Superior and inferior thyroid
- Sup- from external carotid
- Inf- from thyrocervical

N- Middle cervical ganglion, inferior cervical ganglion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Histology of parathyroid

A

Cells are densely packed compared to the follicular thyroid cells.

Chief cells
- Produces PTH

Oxyphil cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Parathyroid hormone
- Secretion
- Function
- Regulation

A

Secreted from chief cells of the parathyroid gland.

Responsible for the regulation of calcium and phosphate
- Antagonises the function of calcitonin.
- Stimulates osteoclasts to breakdown bone and release calcium= increases calcium.
- Major phosphate regulator, inhibits proximal reabsorption of phosphate in kidneys.
- Activation of Vit D increases intestinal phosphate absorption

Regulation
- Drop in calcium, increases PTH and vice versa.
- Concentration of ionized Ca2+ determines PTH release, sensed by receptors.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Stimulators of PTH secretion

A

Low ca2+

Mild decrease of Mg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Inhibitors of PTH secretion

A

High Ca2+

Calcitrol

Severe decrease of Mg2+

Increase in phosphate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Hypocalcaemia
- Limits
- Causes

A

Serum Ca2+ <2.1

Causes
- Vitamin D deficiency
- Hypoparathyroidism
- Malabsorption (coeliac, crohn’s, bowel surgery)
- Rhabdomyolysis
- Pancreatitis
- CKD
- Hyperphosphataemia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Hypocalcaemia
- Symptoms
- Signs

A

Reduced calcium lowers threshold potential for APs as it usually blocks Na+ from binding.
- Leads to multiple neuromuscular signs and symptoms

Symptoms and signs
= CATs go numb
- Convulsions
- Arrhythmias
- Tetany
- Numbness in hands, feet, perioral.

Signs
- Tetany
- Depression
- Carpopedal spasm
- Trousseau’s and chvostek’s sign
- Increase QT interval.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Treatment of hypocalcaemia
- Mild
- Severe

A

Mild
- Oral calcium

Severe
- IV Ca gluconate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Hypercalcaemia
- Range
- Causes

A

Ca+ >2.6

Causes
- Primary Hyperparathyroidism
- Hypophosphataemia
- Malignancy: bone, myeloma.
- Vit d toxicity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Hypercalcaemia signs and symptoms

A

Stones, bones, groans, thrones and psychiatric undertones:

Stones= kidney stones, biliary stones

Bones= bone pain

Groans= Abdominal pain, constipation

Thrones= Polyuria

Psychiatric undertones= depression, anxiety, cognitive dysfunction.

Others
- Cardiac arrest
- weight loss, weakness
- vomitting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Primary hyperparathyroidism
- Definition
- Causes
- Signs and symptoms

A

Excess production of PTH from the PT gland.
- Defined by high Ca2+ and high/normal PTH.

Causes
- Adenoma (most common)
- Hyperplasia
- PT carcinoma
- Multiple endocrine neoplasia

Signs and symptoms
- Signs of hypercalcaemia (stones, bones, groans, thrones and psychiatric overtones)
- Hypertension

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Primary hyperparathyroidism investigations

A

Blood test
- Ca2+= very high
- Low PO4
- Abnormal PTH compared to ca2+ levels (should be low)
-

ECG
- Short QT
- Bradycardia
- 1st degree block

DEXA
- osteoporosis

ALP
- Increased due to bone activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Treatment of primary hyperparathyroidism

A

Medical
- Increase fluid intake
- Avoid foods high in Ca2+
- Avoid thiazides

Surgical
- Excision of adenoma
- Indications: high serum or urinary Ca2+, bone disease/ osteoporosis, kidney stones, decreased kidney function, <50
- complications: hypoparathyroidism, recurrent laryngeal n. palsy.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Secondary hyperparathyroidism
- Definition
- Causes

A

Hypocalcaemia leading to high PTH levels

Causes
- Vitamin D deficiency
- Chronic renal failure
- Malabsorption (crohn’s, coeliac, chronic pancretitis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Secondary hyperparathyroidism
- Signs and symptoms

A

Signs and symptoms correspond with signs of hypocalcaemia

Hyperphosphataemia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Treatment of secondary hyperparathyroidism

A

Correct underlying causue

Phosphate binders
- Calcichew (with Ca0)
- Without ca2+: sevelamer, lanthanum

Vit.D
- Calcitrol (active)
- Cholecalciferol (inactive)

17
Q

Hypoparathyroidism
- Definition
- Causes

A

Low PTH due to glandular failure

Causes
- Autoimmune (i.e. autoimmune polyendocrine syndromes)
- Congenital (DiGeorge)
- Iatrogenic: surgery, radiation.

18
Q

Congenital causes of hypoparathyroidism

A

DiGeorge’s (Chromosome 22)

Tetrology of Fallot’s

Thymic aplasia

Cleft palate

19
Q

Secondary hypoparathyroidism

A

Secondary causes of low PTH

Causes
- Surgery
- Radiation
- Low Mg

20
Q

Pseudohypoparathyroidism
- Description
- Signs
- Investigation findings

A

Failure of target cells to respond to PTH due to genetic cause

Signs
- Short 4th and 5th metacarpals
- round face
- short stature
- calcified basal ganglia

Investigations
- PTH elevated
- HypoCa2+
- ALP normal/ elevated

21
Q

Pseudopseudohypoparathyroidism
- Description

A

Morphological feature of pseudohypoparathyroidism with normal biochemistry
- Has skeletal defects with normal Ca and PTH

22
Q

Multiple endocrine neoplasia
- Type 1

A

Syndrome of hormone producing tumours
- Inherited in autosomal dominant fashion
- MEN-1 is a tumour suppressor gene

MEN-1 tumors
- Parathyroid hyperplasia/ adenoma
- Pancreas endocrine tumours: glucagonoma, gastrinoma, insulinoma.
- Pituitary adenoma

23
Q

Multiple endocrine neoplasia
- Type 2

A

MEN-2 cancers
- Thyroid medullary carcinoma
- Pheochromocytoma (benign and bilateral)
- parathyroid hyperplasia

24
Q

What is the medical treatment of acute, mild hypocalcaemia (>1.9)

A

Oral calcium supplement
- Adcal, Calcichew

Vitamin D supplement (if they are deficient)

Correct any magnesium deficiency

25
Q

What is the medical treatment of acute, severe hypocalcaemia (<1.9)

A

IV calcium replacement
- 10mL of 10% calcium gluconate over 10 mins
- In 50-100mL of 5% dextrose

Follow up with
- 100mL of 10% calcium gluconate
- In 1L of saline