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Endocrine System > Lecture 24 Clinical Calcium Homeostasis > Flashcards

Lecture 24 Clinical Calcium Homeostasis Flashcards

1
Q

Name dietary sources of calcium

A
  • Milk, cheese and other dairy foods
  • Broccoli, Cabbage and Okra
  • Soya beans
  • Tofu
  • Nuts
  • Bread and anything with fortified flour
  • Fish where you eat the bones- sardines and pilchards
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2
Q

What are the functions of calcium

A
  • Bone formation
  • Cell division & growth
  • Muscle contraction
  • Neurotransmitter release
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3
Q

What percentage of calcium is found in the
Cells
ECF
Bone

A

Cells-1%
ECF- 0.1%
Bone- 98.9%

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4
Q

In the plasma what percentage of calcium is bound to albumin, non-ionised and ionised

A
  • 45% bound mainly to albumin
  • 10% non-ionised or complexed to citrate PO4
  • 45% ionised (biologically important)
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5
Q

What is the normal calcium range in the plasma

A

2.20-2.60 mmol/l

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6
Q

How do you calculate free calcium

A

– Adjust Ca2+ by 0.1mmol/l for each 5g/l reduction in albumin from 40g/l
Ca (mmol/L) = Ca measured (mmol/L) + 0.020 (40 - albumin (g/L))].

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7
Q

Name sources of vitamin D

A
  • Oily fish – such as salmon, sardines and mackerel
  • Eggs
  • Fortified fat spreads
  • Fortified breakfast cereals
  • Some powdered milks
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8
Q

Name groups at risk of vitamin D

A
  • Pregnant
  • Children
  • Elderly
  • Black
  • Asian
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9
Q

When is PTH secreted

A

In réponse to low calcium from the parathyroid Gand

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10
Q

Explain Vitamin D metabolism

A
  1. Vit D is metabolised first to 25 hydroxyvitaimn D
  2. Transported to kidneys where it is converted to active form under the influence of parathyroid hormones
  3. Effects of this are mineralisation of bone, increased calcium and phosphate reabsorption in the kidneys and increased calcium absorption in the gut
  4. Excess Vit D is excreted into the bile
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11
Q

What are the neurological symptoms of acute hypocalcaemia

A 
Tetany
Parathesia
Muscle twitching
Carpopedal Spasm
Trousseau's sign
Chovstek's sign
Seizures
Laryngospasm
Bronchospasm
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12
Q

What are the cardiac symptoms of acute hypocalcaemia

A

Prolonged QT interval
Hypotension
Heart failure
Arrythmia

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13
Q

What causes low PTH

A 
Direct damage to Parathyroid gland
Post surgical
Autoimmune
Infiltration
Radiation induced
HIV infection
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14
Q

What causes high PTH

A 
In response to hypocalcaemia caused by
Renal disease
Vitamin D deficiency 
Hypomagnesium
Acute respiratory alkalosis
cute pancreatitis
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15
Q

What drugs can cause hypocalcaemia

A 
Bisphophates
Calcitonin
Cinacalet
Calcium chelators
Foscarnet
Ohenytoin
Fluoride poisoning
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16
Q

What investigations can be done if hypocalcaemia is detected

A
  • Ca & Vit D intake
  • Neck surgery
  • Autoimmune disorders
  • Medications
  • Family history
  • Neck scars
  • ECG- Calcium plays a key role in cardiac muscle contraction and metabolism, abnormal heart rate, slow it down
  • Serum calcium
  • Albumin
  • Phosphate
  • PTH
  • U&Es
  • Vitamin D
  • Magnesium
17
Q

What is Pseudohypoparathyroidism

A

Presents at childhood
Target organ (kidney and bone) unresponsiveness to PTH
hypocalcemia, hyperphosphatemia
Elevated PTH

18
Q

How is mild hypocalcaemia treated

A

oral calcium
If vitamin D deficient treat with supplement
If low magnesium- replace magnesium

19
Q

How is severe hypocalcaemia treated

A

IV calcium gluconate

ECG monitoring

20
Q

Who should be taking Vitamin D supplements and how mcuh

A

• Everyone age 5 years and above should consider taking a daily supplement of 10 micrograms vitamin D, particularly during the winter months (October – March).

21
Q

What are the causes of hypercalcaemia

A 
Sporadic
malignancy
Vitamin D intoxication
Chronic granulomatous disorders (TB, sarcoidosis, Wegner's)
Hyperthyroidism
Acromegaly
22
Q

Clinical features of hypercalcaemia

A 
Polyuria
Polydipsia
Anorexia
Nausea and vomiting
Muscle weakness
Decreased concentration
Shortening of the QT interval
23
Q

What is the management of multiple endocrine neoplasia

A
  • 0.9% Saline 4-6 litres over 24 hours
  • Monitor for fluid overload
  • Consider dialysis if severe renal failure
  • After rehydration, intravenous bisphosphonates
  • Zolendronic acid 4mg over 15 mins
  • Give more slowly and consider dose reduction if renal impairment
  • Calcium will reach nadir at 2-4 days
24
Q

Whats the 2nd line management for MEN

A

Glucocorticoids- lymphoma, granulomatous disease, Vit D poisoning
Calcitonin- if there’s poor response to bisphosphates
Calcimimetics- hypercalcaemia
Parathyroidectomy- acute presentation of primary hyperparathyroid

Endocrine System (26 decks)

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