disorders of calcium homeostasis part 2 W2

Question 1

what causes the symptoms of hypocalcaemia

Answer 1

increase in neuromuscular excitability due to increased inward Na+ movement.
resting potential of membrane is increased in hypocalcaemia
action potentials may be spontaneously generated

Question 2

neuromuscular clinical manifestations of hypocalcaemia?

Answer 2

numbness and paraesthesia (tingling) in fingertips, toes, around mouth
anxiety and fatigue
muscle cramps, carpo-pedal spasm, bronchial or laryngeal spasm
seizures

Question 3

clinical manifestations of hypocalcaemia - mental state?

Answer 3

personality change
confusion, psychoneurosis
impaired intellectual ability

Question 4

clinical manifestations of hypocalcaemia other than neuromuscular and mental state

Answer 4

ECG changes (prolongation of QT interval) - can lead to cardiac arrest
eye problems - cloudiness

Question 5

Chvostek’s sign?

Answer 5

contraction of muscles of eyes/mouth/nose elicited by tapping along the course of the facial nerve (in front of ear)

Question 6

neurological signs of hypocalcaemia?

Answer 6

Chvostek’s sign
Trousseau’s sign

Question 7

Trousseau’s sign

Answer 7

bp cuff used, brachial artery occluded for 3 minutes.
causes involuntary spasm of muscles resulting in adducted thumb, grouped fingers, flexed wrist

Question 8

factitious hypocalcaemia causes?

Answer 8

consequence of low plasma albumen
-acute phase response
-malnutrition/malabsorption
-liver disease
-nephrotic syndrome

Question 9

common cause of hypocalcaemia

Answer 9

vitamin D deficiency!! caused by

lack of sunlight exposure
inadequate dietary source
malabsorption
chronic renal disease (common)
chronic liver disease (rare)
rare genetic causes

Question 10

vitamin D deficiency risk factors?

Answer 10

those confined indoors (esp elderly)
dark skin
high latitudes
lack of sunlight exposure (via dress, suncream, etc)

Question 11

biochemical features of vitamin D deficiency

Answer 11

low 25-D3 and 1,25-D3 (
low Ca2+
high PTH
phosphate tends to be low
often raised ALP

Question 12

clinical features of vitamin D deficiency

Answer 12

symptoms related to low Ca2+
osteomalacia (bone pain, fractures disordered growth in children as a consequence of defective mineralisation)

Question 13

what is osteomalacia called in children?

Answer 13

Rickets

Question 14

osteomalacia pathophysiology?

Answer 14

pathological bone problem classically associated with vitamin D deficiency
osteoid laid down by osteoblasts is not adequately calcified
osteoid content in bone increases as expense of normal calcified osteoid (bone matrix)
bones are softened, weak and susceptible to fracture

Question 15

inherited causes of osteomalacia/rickets?

Answer 15

deficient 1-hydroxylase (vitamin D-resistant rickets type 1)

defective receptor for calcitriol (vitamin D-resistant rickets type 2)

Question 16

hypoparathyroidism causes

Answer 16

acquired
-surgical damage/removal
-suppressed secretion

inherited
-developmental parathyroid problems
-genetic/familial disorders

Question 17

hypoparathyroidism biochemistry?

Answer 17

low Ca2+
inappropriately low PTH
phosphate may be increased

Question 18

what is magnesium required for

Answer 18

required for PTH action

Question 19

what can cause suppressed secretion in acquired hypoparathyroidism

Answer 19

low magnesium
maternal hypercalcaemia

Question 20

treatment of hypocalcaemia

Answer 20

acute - IV calcium
normally oral calcium and vitamin D are given (sometimes Mg)
vitamin D given in various forms
-by injection if malabsorption
-as 10H form if renal function
impaired
close monitoring of plasma calcium concentration necessary

Question 21

osteoporosis features

Answer 21

reduced bone mineral density, disruption of microarchitecture
routine biochemistry unaffected

Question 22

osteoporosis vs osteomalacia in terms of biochemistry

Answer 22

osteoporosis - normal biochem
osteomalacia - abnormal biochem