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Endocrinology > Parathyroid disorders > Flashcards

Parathyroid disorders Flashcards

1
Q

What mineral decreases parathyroid hormone secretion?

A

Calcium

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2
Q

What are some symptoms of hypercalcaemia?

A

Bones - Bone pain
Stones - Kidney stones
Abdominal groans - Constipation
Thrones - Polyuria
Psychiatric moans - Depression, anxiety

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3
Q

What are some acute signs of hypercalcaemia?

A
  • Thirst
  • Dehydration
  • Confusion
  • Polyuria
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4
Q

What are some chronic presentations of hypercalcaemia?

A
  • Myopathy
  • Fractures
  • Osteopenia
  • Depression
  • Hypertension
  • Pancreatitis
  • Renal calculi
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5
Q

What is hypocalcuric hypercalcaemia?

A

This is an autosomal dominant, deactivating mutation in calcium sensing receptors

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6
Q

What are some presentations of hypocalcuric hypercalcaemia?

A

Mild hypercalcaemia
Reduced urine calcium excretion
Marginally elevated PTH

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7
Q

What are soem causes of hypercalcaemia?

A

Primary and tertiary hyperparathyroidism
Malignancy
Drugs
Granulomatous disease
Hypocalcuric hypercalcaemia
Milk-Alkali syndrome (Too many antacids)
MEN1/2

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8
Q

What are some drugs that can cause hypercalcaemia?

A

Vitamin D
Thiazides

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9
Q

What are the mechanisms of hypercalcaemia in malignancy?

A

Metastatic bone restructure, PTHrp release and osteoclast activating factor release by tumours causes increased release of bone stored calcium into the blood

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10
Q

How will hypercalcaemia of malignancy be diagnosed?

A

Raised calcium
Raised ALP
X-ray, CT, MRI or PET showing tumour
Isotope bone scanning

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11
Q

Give the cause of hypercalcaemia:

High/Normal PTH
High Urine Ca2+ excretion

A

Primary/Tertiary hyperparathyroidism

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12
Q

Give the cause of hypercalcaemia:

High/Normal PTH
Low urine Ca2+ excretion

A

Familial Hypocalcuric hypercalcaemia

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13
Q

Give the cause of hypercalcaemia:

Low PTH
High phosphate
Raised ALP (Bone pathology)

A

Metastases
Sarcoidosis
Thyrotoxicosis

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14
Q

Give the cause of hypercalcaemia:

Low PTH
High phosphate
Low ALP (No bone pathology)

A

Myeloma
Vitamin D toxicity
Milk-alkali syndrome

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15
Q

How should hypercalcaemia be acutely managed?

A

Fluids (0.9% saline 4-6L 24hours)
Consider loop diuretics (Not thiazides)
Bisphosphonates
Steroids possible (E.g. Prednisolone in sarcoidosis)

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16
Q

What are some causes of hypocalcaemia?

A
  • Chronic kidney disease
  • Congenital absence (DiGeorge syndrome)
  • Destruction (surgery, radiotherapy, malignancy)
  • Autoimmune
  • Hypomagnesaemia - calcium release from cells is dependent on magnesium
  • Idiopathic
  • Pseudohypoparathyroidism and pseudo-pseudohypoparathyroidism
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17
Q

What are some symptoms of hypocalcaemia?

A
  • Paraethesia - fingers, toes, perioral
  • Muscle cramps, tetany
  • Muscle weakness
  • Fatigue
  • Bronchospasm or laryngospasm
  • Fits
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18
Q

What are some clinical signs of hypocalcaemia?

A
  • Chovesteks sign - gentle tapping over the facial nerve causes twitching of the ipsilateral facial muscles
  • Trousseau sign - inflation of the sphygmomanometer cuff above systolic pressure for 3 min induces tetanic spasm of the fingers and wrist
  • ECG - QT prolongation
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19
Q

How is acute severe hypocalcaemia managed?

A
  • IV calcium gluconate 10 ml, 10% over 10 mins (in 50ml saline or dextrose)
  • Calcium infusion (10ml 10% calcium gluconate in 100ml infusate, at 50 ml/h)
20
Q

How is hypocalcaemia treated in the long term?

A
  • Calcium supplement >1-2g PO/day
  • Vitamin D
    • 1 alphacalcidol 0.5-1 mcg PO/day OR
    • Depot injection: cholecalciferol 300 000 units 6 monthly
21
Q

What is meant by primary hyperparathyroidism?

A

This is hyperparathyroidism caused by uncontrolled parathyroid hormone produced directly by a tumour of the parathyroid gland (E.g. Parathyroid adenoma)

22
Q

What metabolic change will result from hyperparathyroidism?

A

Hypercalcaemia

23
Q

How is primary hyperparathyroidism diagnosed?

A

Raised serum calcium
Raised serum PTH
Increased urine calcium excretion

24
Q

How is primary hyperparathyroidism managed?

A

Surgical tumour removal
Symptomatic relief with cinacalcet (Calcium mimic)

25
Q

What is secondary hyperparathyroidism?

A

This is parathyroid overactivity caused by infusfficient vitamin D or chronic renal failure, which lead to low calcium absorption from the intestines, kidneys and bones, leading to hypocalcaemia

26
Q

How will secondary hyperparathyroidism show on blood testing?

A
  • Low calcium
  • High PTH
27
Q

How is secondary hyperparathyroidisim managed?

A

Correcting the vitamin D deficiency or performing a renal transplant to treat renal failure

28
Q

What is tertiary hyperparathyroidism?

A

This is parathyroid overactivity that occurs when secondary hyperparathyroidism continues for a long period of time (e.g. renal failure), leading to hyperplasia of the glands

The parathyroid becomes autonomous after many years of overactivity

29
Q

How will tertiary hyperparathyroidism show on blood tests?

A

High PTH
High Calcium

30
Q

How is tertiary hyperparathyroidisim managed?

A

Surgical removal of part of the parathyroid tissue to return the parathyroid hormone to an appropriate level

31
Q

What are some functions of parathyroid hormone?

A
  • Osteoclast activation (Increased bone reabsorption and thus calcium release)
  • Increased reabsorption of calcium by the renal tubules
  • Increased urinary phosphate excretion
  • Increased synthesis of active forms of vitamin-D
32
Q

What is fibrosa cystica?

A

This is a condition that occurs when unchecked hyperparathyroidism results in overproduction of PTH and continued osteoclasis

33
Q

What are the 3 main conditions of fibrosa cystica?

A

Osteoporosis
Brown tumour formation
Osteitis

34
Q

How do brown tumours form?

A

Osteoporotic bone is prone to fracture
Associated haemorrhage elicits a macrophage reaction and processes of organisation and repair
This results in a mass of reactive tissue known as a brown tumour

35
Q

What are some indications of parathyroidectomy?

A
  • End organ damage
    • Bone disease
    • Gastric ulcers
    • Renal stones
  • Very high calcium (>2.85mmol/L)
  • Under 50 y/o
  • eGFR <60mL/min
36
Q

What are some causes of hypomagnesemia?

A
  • Alcohol
  • Drugs - thiazide, PPIs
  • GI illness with diarrhoea
  • Pancreatitis
  • Malabsorption
37
Q

What are some symptoms of hypomagnesaemia?

A
  • Anorexia
  • Nausea and vomiting
  • Muscle weakness, lethargy
  • Fits
38
Q

What are some clinical signs of hypomagnesaemia?

A
  • Cardiac arrhythmias
  • Positive Chovestek sign and Trousseau sign indicate secondary hypocalcaemia
39
Q

How is hypomagnesaemia managed?

A

Magnesium supplementation
Calcium supplementation if needed

40
Q

What is the main complication of hypermagnesaemia?

A

Secondary hypocalcaemia

41
Q

How does hypomagnesaemia lead to hypocalcaemia?

A
  • Calcium release from cells is dependent on magnesium
  • In magnesium deficiency intracellular calcium is high
  • PTH release inhibited
  • Skeletal muscle receptors less sensitive to PTH
42
Q

What is pseudohypoparathyroidism?

A

Condition associated primarily with resistance to the parathyroid hormone

43
Q

Describe the genetics of pseudohypoparathyroidism

A

Dysfunction of Gs alpha subunit (GNAS 1 gene), which is coupled to the PTH receptor

44
Q

How will pseudohypoparathyrodisim present?

A
  • Bone abnormalities (McCune Albright)
  • Obesity
  • Subcutaneous calcification
  • Learning disability
  • Brachdactyly (shortened 4th metacarpal)
45
Q

How will pseudohypoparathyroidism show in blood tests?

A

calcium will be low but PTH concentrations are elevated due to PTH resistance

46
Q

What is pseudo-pseudohypoparathyroidism?

A
  • Describes the phenotypic defects of pseudohypoparathyroidism (Albright’s herditary osteodystrophy) but without any abnormalities in calcium metabolism
  • Individuals with this condition may share the same gene defect as those with pseudohypoparathyroidism and be members of the same families
47
Q
A

Endocrinology (42 decks)

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