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ENDOCRINOLOGY& DIABETES > Endocrine Disease III > Flashcards

Endocrine Disease III Flashcards

1
Q

How much Ca does the average person have?

A

1kg - 99% of skeleton

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2
Q

Functions of calcium?

A

Cofactor in coagulation
Skeletal mineralisation
Membrane stabilisation

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3
Q

How is Ca homeostasis achieved?

A

Ca is transported to and from the kidney, intestine and bone
Decreased serum Ca = increase PTH
= Increased bone resorption, increase Ca reabsorption and increase Ca absorption

= negative feedback - returns sCa conc to 1.1mmol/l

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4
Q

What does the PTH also do?

A

Reduce phosphate reabsorption

Increase 1apha- hydroxylation of 25-OH vit D

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5
Q

What is calcium homeostasis and example of?

A

Neg feedback = return serum ionised calcium back to 1.1mmol/l

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6
Q

Why can abnormalities in PTH occur?

A

Appropriate: to maintain Ca balance
Inappropriate: cause calcium imbalance

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7
Q

How does sCa conc impact PTH conc?

A

High sCa = low PTH
Low sCa = high PTH
If normal = equal concs

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8
Q

What is hypocalcaemia?

A

Low serum calcium

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9
Q

Causes of hypocalcaemia?

A 
• Vitamin D deficiency/Osteomalacia
• Hypoparathyroidism
– post surgery, radiation, autoimmune disease
– Hereditary (Autosomal dominant
hypocalcaemia)
– Syndromes (Di George, HDR [hypopara,
deafness, renal dysplasia] etc)
– Infiltration (Wilson’s disease,
haemochromatosis)
• Chronic renal failure
• Magnesium deficiency
• Pseudohypoparathyroidism
• Acute pancreatitis
• Multiple citrated blood transfusions
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10
Q

Consequences of hypocalcaemia?

A 
• Paresthesia (burning sensation)
• Muscle spasm
– Hands and feet
– Larynx
– Premature labour
• Seizures
• Basal ganglia
calcification
• Cataracts
• Dental hypoplasia
• ECG abnormalities
– Long QT interval
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11
Q

How to look for clues relating to hypocalcaemia?

A 
History of neck surgery
Presence of other autoimmune conditions
History of congenital defects and immunodeficiency
Family history = genetic cause
Neck scar
Growth failure, hearing loss
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12
Q

PTH, Ca and phosphate levels in vitamin D deficiency? (2ndry hyperparathyroidism)

A

Increased PTH, decreased CA and phosphate

PTH appropriate

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13
Q

How does hypoparathyroidism cause low sCa levels?

A

Low PTH
= Low renal ca reab = increase ca excretion
= Low renal phosphate reab = high serum phosphate
= Decreased bone resorption
= Increased formation of 1,25(OH)2D = decreased intestinal ca reab

= Low sCa

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14
Q

What is Pseudohypoparathyroidism?

A

Resistance to parathyroid hormone:
Type 1 - mutation with deficient Galpha subunit
1a Albright hereditary osteodystrophy

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15
Q

Clinical features of Pseudohypoparathyroidism?

A
  • Short stature
  • Obesity
  • Round facies
  • Mild learning difficulties
  • Subcutaneous ossification
  • Short fourth metacarpals
  • Other hormone resistance
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16
Q

PTH, Ca and phosphate levels in hypoparathyroidism?

A

Low PTH and Ca, high phosphate

Inappropriate PTH

17
Q

PTH, Ca and phosphate levels in Pseudohypoparathyroidism?

A

High PTH, low Ca, high Phosphate

Appropriate PTH

18
Q

How to manage hypocalcaemia?

A

If symptomatic or Ca less than 1.9mmol/l:
- IV Ca gluconate for 10 mins (10% soln 10mins)
OR
- Vitamin D tx

19
Q

Causes of hypercalcaemia?

A 
Malignancy - bone mets, myeloma, PTHrP, lymphoma = 90% causes
Primary hyperparathyroidism
Benign hypercalcaemia 
Thiazides
Sarcoidosis
Immobilisation
Adrenal insufficiency
20
Q

Symptoms and consequences of hypercalcaemia?

A 
• Thirst, polyuria
• Nausea
• Constipation
• Confusion coma
• Pancreatitis
• Gastric ulcer
• Renal stones
• ECG abnormalities
- Short QT
21
Q

Signs of hypercalaemia?

A 
• Confusion, hypotonia, hyporeflexic
• Dehydration
• Signs of malignancy (enlarged liver,
clubbing, thyroid mass, breast lump,
lymph nodes)
• Faecal impaction
• Irregular pulse (arrhythmia)
22
Q

Approach to hypercalcaemia?

A

Identify drugs causing it (thiazides, vit D)
Identify presence of renal failure? - Tertiary hyperparathyroidism
Check serum PTH and 24hr urine Ca excretion

If PTH high or normal and urine calcium excretion > 0.01 mmol/l – Primary
Hyperparathyroidism
• If PTH high or normal and urine calcium excretion < 0.01 mmol/l – FHH
• If PTH low or suppressed – exclude malignancy,
hyperthyroidism, Addison’s, sarcoidosis, granulomatous
disorders

23
Q

What occurs to sCa when there is a malignancy causing hypercalcaemia?

A

increase sCa
= decrease PTH
= decrease bone resorption, ca absorption and ca reab

24
Q

Hypercalcaemia of malignancy?

A

About 20 to 30% of patients with cancer
• 80% are due to bony metastases (breast, thyroid , kidney,
lung, prostate)
• 20% due to PTHrP release (others secrete Vitamin D,
ectopic PTH)
• Osteoclastic Hypercalcaemia

25
Q

PTH, Ca and phosphate levels in hypercalcaemia of malignancy?

A

Low PTH, high Ca, N Phosphate, appropriate PTH

26
Q

Causes of primary hyperparathyroidism?

A

80% due to single benign adenoma
15-20% due to 4 gland hyperplasia
<0.5% malignant

27
Q

Consequences of primary hyperparathyroidism?

A 
• Bones
– Osteitis fibrosa cystica
– Osteoporosis
• Kidney stones
• Psychic groans
– confusion
• Abdominal moans
– Constipation
– Acute pancreatitis
28
Q

How does primary hyperparathyroidism result in hypercalcaemia?

A

High PTH
increase ca reab
Increase bone resorption
Increase renal reabsorption of ca

29
Q

Management of primary hyperparathyroidism?

A

Indications for surgery
• Serum calcium > 0.25 mmol/l from upper limit
• Creatinine clearance < 60 ml/min
• T-score < -2.5 at any site and/or previous fragility
fracture at spine, hip, radius, femoral neck
• 24 hour urine calcium >400mg/day (>10mmol/day)
• Nephrocalcinosis or nephrolithiasis
• < 50 years

30
Q

PTH, Ca and Phosphate levels in primary hyperparathyroidism?

A

High PTH, High Ca, low phosphate, inappropriate PTH

31
Q

What occurs in tertiary hyperparathyroidism?

A 
Renal failure
= Vit D deficiency
= Low Ca absorption
= Decrease sCa
= INcrease PTH
= Decrease serum phosphate
= impaired mineralisation
= high alkaline phosphatase 
= nodular hyperplasia
32
Q

PTH, Ca and Phosphate levels in tertiary hyperparathyroidism?

A

High PTH, Ca and phosphate

Inappropriate PTH

33
Q

Management of hypercalcaemia?

A

• Intravenous fluids Normal 0.9% saline
• Loop diuretic if risk of overload ONLY
• Intravenous bisphosphonates e.g
pamidronate,
zoledronic acid (make sure PTH sample taken)
• Corticosteroids e.g Vitamin D intoxication,
sarcoidosis

ENDOCRINOLOGY& DIABETES (4 decks)

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