Calcium metabolism

Question 1

What are the roles of the following in Ca levels and where are they synthesised?
- PTH
- Calcitriol (activated Vit D)
- Calcitonin
What cancer is calcitonin a tumour marker in?

Answer 1

• PTH: parathyroid gland, raise Ca.
• Calcitriol: Skin + UV light, raise Ca more than PTH.
• Calcitonin: parafollicular cells, reduce Ca. Tumour marker in medullary thyroid cancer.

Question 2

What is pathway to activate dietary/ UV Vit D?

Answer 2

• Vit D + (25-hydroxylase)
• 25-(OH)D3 + (1a-hydroxylase) + (PTH)
• Calcitriol,

Question 3

What occurs in primary hyperparathyroidism?
What is PTH level? What is ALP level?
Give 2 risk factors.
What signs and symptoms are associated?

Answer 3

• Overactive (hyperplasia) parathyroid gland, no negative feedback from raised calcium levels. High serum, Ca
• PTH and ALP level is high OR NORMAL
  RF:
• MEN 1 or MEN 2
• Hypertension

Symptoms of hypercalcaemia: stones, bones, thrones abdominal moans, psychic groans.

Question 4

What are the symptoms of low calcium? (CATs go numb).

Give 2 signs of hypocalcaemia.

Answer 4

Hypocalcaemia:

• Convulsions
• Arrhythmias- prolonged QT interval
• Tetany
• Paraesthesia- hands, feet, mouth, lips.
• Trousseau’s sign
• Chvostek’s sign

Question 5

What are the symptoms of hypercalcaemia?

What condition may it cause?

Answer 5

Stones, bones, thrones, abdominal moans, psychic groans.

• Renal stones
• Bone pain/ damage
• Polyuria
• Abdo upset (nausea, constipation, pain).
• Psychiatric conditions: depression, anxiety.

May cause pancreatitis.

Question 6

What occurs in secondary hyperparathyroidism?
Which enzyme in Calcitriol synthesis is lost in CKD?
Which enzyme is lost in liver disease?

Answer 6

• (reduced renal function/ low Vit D), initial low Ca levels cause increased PTH secretion. Low serum Ca.
• 25-hydroxylase made in liver.
• 1a- hydroxylase made in kidney.

Question 7

Give 3 general signs other than hypocalcaemia in secondary hyper parathyroidism.
Which bone condition is associated with secondary hyperparathyroidism?

Answer 7

• Fractures/ bone pain
• Proximal myopathy
• Fatigue
• Osteomalacia/ rickets in children.

Question 8

Give 2 causes of osteomalacia. What is phosphate level in both?

Answer 8

• Vit D deficiency: low phosphate

- CKD (no 1a-hydroxylase): high phosphate- no excretion.

Question 9

Give skull x-ray finding in primary HPT.
Give a chest x-ray finding of secondary HPT.
Give a long bone x-ray finding of secondary HTP.

Answer 9

• Primary skull: pepper pot skull.
• Secondary chest: rachitic rosary.
• Secondary long bone: Looser’s pseudo fractures.

Question 10

What is acute management of primary hyperparathyroidism?

• Give 1st line management of 1 HPT
• Give secondary management of 1 HPT.

Answer 10

Management is reduce hypercalcaemia.

• Acute: IV fluids, bisphosphonates if Ca remains high.
• 1st line: surgery: total parathyroidectomy.
• 2nd line: Medical (if not suitable for surgery). Cinacalcet: calcimimetic.

Question 11

What is acute management of secondary Hyperparathyroidism?
What is medical management?
What is management of osteomalacia due to CKD?

Answer 11

Synonimise secondary HPT with Osteomalacia. Treat hypocalcaemia.

• Acute: IV calcium infusion- calcium gluconate- also red in treatment for hyper K+.
• Medical: Calcium, Vit D- inactive (ergocalciferol)
• CKD osteomalacia: Treat CKD. Calcium. Vit D- active, alfacalcidol

Question 12

What are the 3 phases in Paget’s disease?

Answer 12

1. Lytic phase: hyperactive osteoclasts
2. Mixed phase: compensation by osteoblasts
3. Sclerotic phase: hyperactive osteoblasts- woven bone formation, not lamellar.

Question 13

Give symptoms of Paget’s disease.
Give 3 signs of Paget’s disease.
More polyostotic or monostotic?

Answer 13

• Bone pain, insidious onset in femur, pelvis, skull.
• Nerve compression: sensorineural hearing loss, sciatica.
• Bone bossing: skull, femur, tibia.
• Thoracic kyphosis
• Warm skin over painful area: high metabolic activity.

25% monostotic, 75% polostotic.

Question 14

What are serum ions and bone markers are found in Paget’s disease?
Give a bone resorption and formation marker found in Paget’s.
Which bone scan is used in Paget’s other than X-ray- how do lytic areas appear?

Answer 14

• All normal apart from ALP, raised.
• Serum CTX: resorption marker.
• Serum P1NP: formation marker.
  Bone scan: Tec99. Lytic areas are darker, “hot spots”.

Question 15

Give 3 signs/ symptoms of osteoporosis.
What are serum blood results?
Which imaging method is used investigate?
What are the two scores found?

Answer 15

• Fractures
• back pain
• thoracic kyphosis

All results normal including ALP.
- DEXA scan, lower than -2.5 is osteoporosis. T-score is BMD compared to young healthy adult. Z-score is BMD compared to age matched BMD.