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5. Endocrinology > 14. Parathyroid gland disorders > Flashcards

14. Parathyroid gland disorders Flashcards

1
Q

What does the parathyroid gland control?

A

Serum calcium levels

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2
Q

What are the 2 hormones released by the parathyroid gland?

A

PTH - secreted in response to low serum calcium.

Calcitonin - secreted in response to high serum calcium.

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3
Q

Describe the usual function of parathyroid hormone (PTH).

A

Secreted in response to low ionised calcium levels (-ve feedback).

Acts by increasing osteoclastic activity - releases calcium/phosphate from bones.

  1. Increases bone reabsorption
  2. Increases calcium reabsorption in kidneys
  3. Increases Calcitriol production -> then acts on the intestine to increase calcium absorption
  4. Decreases phosphate reabsorption in kidney.

Overall effect = increases calcium, decreases phosphate.

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4
Q

Define hypoparathyroidism.

A

A condition where there is an underproduction of parathyroid hormone

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5
Q

Give 3 causes of primary hypoparathyroidism.

A
  1. Autoimmune polyendocrine syndrome type 1 (destroys PT glands)
  2. DiGeorge syndrome
  3. Autosomal dominant hypoparathyroidism
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6
Q

Give 2 causes of secondary hypoparathyroidism.

A
  1. Radiation
  2. Surgery
  3. Hypomagnesaemia
  4. Removal of PT glands
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7
Q

What is the affect of hypoparathyroidism on serum calcium levels?

A

Hypoparathyroidism -> hypocalcaemia.

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8
Q

What would biochemical tests show in a patient with hypoparathyroidism?

A

Low calcium
Low/normal phosphate

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9
Q

Give 5 causes of hypocalcaemia.

A
  1. Dietary insufficiency.
  2. Anticonvulsant therapy.
  3. CKD.
  4. Vitamin D deficiency.
  5. Osteomalacia.
  6. Hypoparathyroidism.
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10
Q

Give 2 causes of hypocalcaemia with normal/low phosphate.

A
  1. Osteomalacia
  2. Acute pancreatitis
    (FFAs bind to calcium)
  3. Over-hydration
  4. Respiratory alkalosis
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11
Q

Give 2 causes of hypocalcaemia with high phosphate.

A
  1. CKD
    (Chronic kidney disease -> lack of reabsorption)
  2. Hypoparathyroidism
  3. Acute rhabdomyolysis
    (cells die and release phosphate and binds to calcium and making in insoluble)
  4. Vitamin D deficiency
  5. Hypomagnesaemia
    (needed for PTH secretion)
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12
Q

Give 5 clinical features / signs of hypocalcaemia (hypoparathyroidism)?

A

SPASMODIC:
Spasms.
Perioral paraesthesiae.
Anxious, irritable, irrational.
Seizures.
Muscle tone increased in smooth muscle - colic, wheeze, dysphagia.
Orientation impaired (time, place and person) and confusion.
Dermatitis.
Impetigo herpetiformis.
Chvostek’s sign, choreasthetosis, cataract, cardiomyopathy.

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13
Q

What is Chvostek’s sign and what does it indicate?

A

When facial nerve is tapped at the angle of the jaw, facial muscles on the same side of the face contract.

-> Indicates nerve hyperexcitability due to hypocalcaemia.

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14
Q

What is Trousseau’s sign and what does it indicate?

A

BP cuff causes wrist to flex and fingers to draw together.

-> Indicates nerve hyperexcitability due to hypocalcaemia.

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15
Q

Investigations for hypoparathyroidism / hypocalcaemia.

A

Hyoparathyroidism -> hypocalcaemia and so:

Bloods
→ low calcium. check PTH, VitD, albumin, phosphorus, magnesium

ECG
1. Small T waves
2. Long QT interval

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16
Q

Treatment of hypoparathyroidism.

A

Treat the hypocalcaemia:

-> Calcium supplements (calcium gluconate):
1. 10ml calcium gluconate/chloride 10% slow IV
2. Oral Calcium

-> Calcitriol (active vitD)

17
Q

Give 2 complications of hypoparathyroidism / hypocalcaemia.

A

Seizure
Cardiac arrest (decreases heart rate and contractility) - a medical emergency!

18
Q

Define hyperparathyroidism.

A

A condition where there is an overproduction of parathyroid hormone.

19
Q

Give 2 causes of primary hyperparathyroidism.

A
  1. Solitary parathyroid adenoma
    - ↑PTH ↑Calcium ↓Phosphate
  2. Malignancy (lung small cell, breast, renal)
  3. Hyperplasia of parathyroid gland.
20
Q

What is the cause of secondary hyperparathyroidism?

A

Physiological compensatory hypertrophy of the gland in an attempt to correct low serum calcium from renal failure

21
Q

What is the cause of tertiary hyperparathyroidism?

A

Prolonged uncorrected hypertrophy
I.E. long term hyperparathyroidism

22
Q

What is the affect of hyperparathyroidism on serum calcium levels?

A

Hyperparathyroidism -> hypercalcaemia

23
Q

Give 3 causes of hypercalcaemia.

A
  1. Primary Hyperparathyroidism.
  2. Hypercalcaemia of malignancy.
    -> Secretion of PTHrP (PTH-related protein)
  3. Vitamin D toxicity.
  4. Myeloma / Lymphoma
24
Q

Give 5 clinical features / symptoms of hyperparathryoidism / hypercalcaemia.

A

Hyperparathyroidism -> hypercalcaemia:

!!Bones, Stones, Psychic Moans and Abdo Groans!!

  1. Bones - pain, cysts, tumours
  2. Stones - renal colic, polyuria, nocturia, haematuria, hypertension
  3. Psychic moans - depression, psychosis, anxiety, malaise
  4. Abdo groans - abdominal pain, nausea, vomiting, constipation, anorexia
25
Q

Investigations of hyperparathyroidism / hypercalcaemia.

A

Hyperparathyroidism -> hypercalcaemia and so:

  1. PTH/bone profile in bloods:
    -> High calcium; High PTH; Low Phosphate
  2. 24h urinary calcium:
    -> High Calcium excretion
  3. ECG:
    - Tall T waves
    - Shorted QT interval
  4. DEXA scan to show any skeletal involvement
  5. Abdo X-ray for renal stones
26
Q

What classical sign is seen on imaging (CT, X-rays) a patient with hyperparathyroidism?

A

Pepper pot skull

  • Multiple tiny well-defined lucencies in the calvaria caused by resorption of trabecular bone in hyperparathyroidism
27
Q

Treatment of hypercalcaemia.

A
  1. IV normal saline.
  2. IV furosemide.
  3. IV calcitonin.
28
Q

Treatment of hyperparathyroidism.

A
  1. Partial/total parathyroidectomy
  2. IV saline
  3. IV bisphosphonates (alendronate).
  4. Cinacalcet - increases sensitivity of parathyroid cells to calcium.
  5. Avoid thiazide diuretics
  6. Low calcium/vit D diet.
29
Q

From what malignancies do you most commonly get hypercalcaemia?

A

Squamous cell lung, breast, bone metastasis, myeloma, GI cancer

30
Q

How does hypercalcaemia of malignancy occur in myeloma?

A

Stimulation of osteoclasts by IL-1 and TNF promotes calcium loss from bones

31
Q

How would you treat hypercalcaemia of malignancy, other than normal malignancy management?

A

Rehydration.
Bisphosphonates - pamidronate (inhibit osteoclast activity)

32
Q

Give 3 symptoms of hypercalcaemia of malignancy

A

Lethargy
Anorexia
Nausea
Polydipsia
Polyuria
Constipation
Dehydration
Confusion
Weakness

5. Endocrinology (20 decks)

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