Calcium In Clinical Practice Flashcards
What is the role of calcium in the clotting cascade=de
Factor IV in teh clotting cascade
EDTA is a calcium chelator
Citrate chelates calcium ions. Need to give recipients of massive blood transfusions intravenous calcium!
What value should she look at in hypercalcaemia
Make sure that you are looking at that adjusted/corrected
serum calcium value!
Describe hospital setting aetiology of hypercalcaemia
• Malignant osteolytic bone metastases
• Multiple myeloma
Common cancers that metastasise to bone causing lytic lesions and hypercalcemia • Breast • Lung • Renal • Thyroid
Prostate cancer is a common cause of bone metastases. However, it causes osteoblastic metastases that do not cause hypercalcemia
What are common sites for metastasis
Common sites for metastases are the vertebrae, pelvis, proximal parts of the femur, ribs, proximal part of the humerus, and skull. More than 90% of metastases are found in this distribution
What is hyperparathyroidism
• Primary – One of the 4 parathyroid glands develops an adenoma
and secretes excessive parathyroid hormone. This causes serum
calcium to rise and serum phosphate to fall
• Secondary – All 4 parathyroid glands become hyperplastic. This is
seen in patients with Vitamin D deficiency. Vitamin D deficiency can
be dietary/environmental or seen in chronic renal failure due to
failure of the 25 hydroxylation of Vitamin D. Vitamin D Deficiency
means that their calcium absorption is low resulting in low serum
calcium levels, that then causes PTH levels to rise. The raised PTH
activates osteoclasts in order to mobilise calcium from bone in an
attempt to maintain normal serum calcium. From the patients
perspective the main problem is bone pain due to osteomalacia in
the case of Vitamin D deficiency and in the case of chronic renal
failure due to renal osteodystrophy
Describe the serum biochemistry of hyperparathyroidism
See slide
What are teh symptoms of primary hyperparathyroidism
• Moans – tired, exhausted, depressed
• Groans – constipation, peptic ulcers, pancreatitis
• Stones – kidney stones. Also polyuria due to impaired sodium and
water reabsorption
• Bones – bone and muscle aches In recent years many patients are asymptomatic having had serum biochemistry for ‘other reasons’
What is the effect of calcium on neuronal activity?
• To understand the symptoms of hypocalcemia hypercalcemia you need to understand that calcium raises the threshold for nerve membrane depolarisation and therefore the development of an action
potential: So:
• Hypercalcemia leads to supression of neuronal activity – lethargy, confusion, coma
• Hypocalcemia leads to ‘excitable’ nerves – tingling, muscle tetany and even epilepsy
What are the symptoms of severe hypercalcaemia??
Symptoms of severe hypercalcemia. Serum calcium > 3.0 mmol/l
• At high calcium levels the polyuria can lead to dehydration which
then exacerbates the hypercalcemis. This can lead to
– Lethargy – Weakness – Confusion – Coma – Renal failure
• Rehydration is the mainstay of treatment
• In patients with malignant hypercalcemia and coma this is not
necessarily a terminal event. After rehydration many can return home
What is symptomatic hypocalcaemia?
• Seen mostly in post total-thyroidectomy patients (because of inadvertant removal/ischaemia of parathyroid glands)
• Symptoms can develop when serum calcium falls below
2.10 mmol/l and can start within 6 hrs of thyroidectomy
What is osteomala is vs osteopiroisis?
• In osteoporosis, there is decreased bone density with a
normal ratio of mineral to matrix. Normal bone, but not
enough of it! It is a process that involves the degeneration of already constructed bone. Leads to brittle bones that are prone to fracture
• In osteomalacia, the ratio of mineral to matrix is decreased (ie there is not enough mineral content
inbone). It is an abnormality that can affect bone building in children (rickets) or bone mineralisation in adults. It leads to soft bones that are prone to bending
Describe osteomalacia
Osteomalacia is due to vitamin D deficiency
• Dietary, environmental. In children it is called rickets • Chronic renal disease – renal osteodystrophy
Osteomalacia in adults causes bone pain, muscle weakness and may lead to deformity
What are teh risk factors for osteoporosis
Risk factors for osteoporosis
• Postmenopausal women • Low body mass index • Long-term oral steroid use • Heavy drinking • Smoking • Low BMI • Prolonged inactivity, such as bed rest
What are the consequences of osteoporosis
Consequences of osteoporosis
• Hip fracture • Wrist fracture • Vertebral crush fractures
