Hypocalcaemia

Question 1

When does the majority of fetal calcium accretion occur?

Answer 1

During the third trimester.

Question 2

What happens to calcium levels within 24 hours after abrupt placental transfer?

Answer 2

They drop.

Question 3

How long does it take for calcium levels to reach levels in older children after the drop?

Answer 3

Two weeks.

Question 4

Why may the measurement of total calcium be misleading?

Answer 4

In states of low albumin.

Question 5

What may happen to total calcium levels in states of low albumin despite normal ionized calcium?

Answer 5

Total calcium may be low.

Question 6

What should be measured in states of hypocalcemia for accurate assessment?

Answer 6

Whole blood ionized calcium.

Question 7

What are the criteria for hypocalcemia in newborns weighing more than 1500g?

Answer 7

Total calcium < 2 mmol/l,
Ionised calcium < 1.1 mmol/l.

Question 8

What are the criteria for hypocalcemia in newborns weighing less than 1500g?

Answer 8

Total calcium < 1.75 mmol/l,
Ionised calcium < 0.9 mmol/l.

Question 9

When are signs of hypocalcemia rare in newborns?

Answer 9

If ionized calcium > 0.8-0.9 mmol/l.

Question 10

Signs of hypocalcaemia

Answer 10

• Jitteriness.
• Neuromuscular irritability.
• High pitched cry.
• Seizures.
• Stridor/ wheezing.
• Tetany.
• Decreased mycocardial function.
  Some newborn infants may be asymptomatic.

Question 11

When is hypocalcemia common in newborns?

Answer 11

Between 12 and 72 hours of life.

Question 12

Which infants are especially prone to hypocalcemia during this time?

Answer 12

Preterm infants.

Question 13

What may be a contributing factor to hypocalcemia during this period?

Answer 13

PTH immaturity.

Question 14

After the initial period, what becomes the primary determinant of calcium levels?

Answer 14

Feeding.

Question 15

When does early hypocalcemia occur?

Answer 15

In the first 2-3 days of life.

Question 16

How is early hypocalcemia characterized in terms of normal physiological changes?

Answer 16

It is an exaggeration of a normal physiological drop.

Question 17

Causes of early hypocalcemia

Answer 17

1. Prematurity
   * 1/3 of preterm infants have low calcium levels.
2. Infant of diabetic mothers (IDM)
3. Perinatal hypoxia
4. Di George syndrome
5. Intrauterine growth restriction
6. Maternal hyperparathyrodism
7. Hypomagnesemia
8. Hypoparathyrodism
9. Maternal Vitamin D deficiency

Question 18

Di George syndrome

Answer 18

• Hypoplastic parathyroid glands.
• 1 in 4000 newborn infants.
• 90%: deletion of 22 q.

Question 19

When does late hypocalcemia occur

Answer 19

Occurs at the end of the first week

Question 20

Causes of late hypocalcemia

Answer 20

1. Vitamin D deficiency
2. High phosphate intake
3. Transfusion with citrated blood
4. Lipid infusions (TPN)
5. Acute renal failure
   * High phosphate

Question 21

High phosphate intake

Answer 21

• Associated with cows milk/cows milk formula.
• Suppresses/antagonises PTH.

Question 22

effects of High phosphate intake

Answer 22

Acute renal failure

Question 23

In which scenarios should calcium, magnesium, and phosphate be monitored?

Answer 23

In certain high-risk scenarios.

Question 24

When should measurement of calcium be considered in newborns?
Answer:

Answer 24

i. Infants with congenital cardiac lesions, especially outflow tract lesions where there is a concern of Di George Syndrome.
ii. Infants showing signs consistent with hypocalcemia.
iii. Infants with hypoxic-ischemic encephalopathy (HIE) being cooled.

Question 25

When might further investigations be necessary for hypocalcemic newborns?

Answer 25

i. If severely symptomatic (e.g., fitting). ii. If early hypocalcemia persists despite treatment. iii. In situations of late hypocalcemia.

Question 26

When should treatment be initiated for hypocalcemic newborns?

Answer 26

For symptomatic newborn infants or those with total serum calcium levels < 1.8 mmol or ionised calcium levels < 0.9 mmol/l.

Question 27

What is the treatment for hypocalcemia in newborns?

Answer 27

Intravenous administration of 10% calcium gluconate, given slowly to avoid bradycardia/asystole.

Question 28

How should the dose of calcium gluconate be administered?

Answer 28

It may be repeated as needed, and maintenance calcium therapy may be initiated.

Question 29

What should be done if neonatal hypocalcemia persists and prolongs?

Answer 29

Investigate for the underlying cause.

Question 30

What is the serum magnesium level indicative of hypomagnesemia?

Answer 30

Serum magnesium < 0.65 mmol/l.

Question 31

Is hypomagnesemia usually found as a standalone condition?

Answer 31

No, it's unusual on its own.

Question 32

With what condition is hypomagnesemia commonly associated?

Answer 32

Persistent hypocalcemia.

Question 33

In which population is hypomagnesemia most commonly seen along with associated hypocalcemia?

Answer 33

Infants of diabetic mothers (IDMs).

Question 34

Besides IDMs, what other conditions might be associated with hypomagnesemia?

Answer 34

Rare disorders of intestinal/renal tubular magnesium transport.

Question 35

How is hypomagnesemia treated?

Answer 35

Intramuscular or slow intravenous administration of magnesium sulfate (MgSO4). Treatment is only required if symptomatic.

Question 36

Definition of hyponatreamia

Answer 36

Serum sodium < 130mmol/l

Question 37

Common causes o hyponatreamia

Answer 37

1. Prematurity. 2. Inadequate sodium intake. 3. Excessive fluid intake. 4. Diuretics. 5. Renal impairment. 6. Gastric losses. 7. SIADH. 8. Congenital adrenal hyperplasia

Question 38

What should be considered if there is weight gain or absence of weight loss along with hyponatremia?

Answer 38

* Consider dilutional causes from fluid overload or CCF or SIADH. * Establish and treat the underlying cause. * Restrict total fluid intake.

Question 39

What steps should be taken if there is weight loss along with hyponatremia?

Answer 39

* Consider sodium losses from osmotic diuresis, diuretics, GIT or renal losses. * Establish the cause. * Supplement sodium either orally or intravenously. * Replace losses and deficit.

Question 40

How should symptomatic hyponatremia or serum sodium < 120mmol/l be managed?

Answer 40

Replace over 24 hours with hypertonic saline after correcting for sodium deficit. However, caution should be exercised to avoid correcting too quickly due to the risk of pontine demyelination.

Question 41

What is the serum sodium level indicative of hypernatremia?

Answer 41

Serum sodium > 145 mmol/l.

Question 42

What conditions are hypernatremia associated with?

Answer 42

Cerebral venous thrombosis and intracerebral bleeds.

Question 43

Common causes of hypernatremia

Answer 43

1. Excessive water loss. 2. Insensible losses from the skin. 3. Gastric losses. 4. Polyuria. 5. Excessive sodium intake.

Question 44

What initial steps should be taken in the management of hypernatremia?

Answer 44

Review for dehydration, assess sources of fluid loss, and evaluate sodium-containing infusions or medications.

Question 45

What should be considered if there is weight loss along with hypernatremia?

Answer 45

a. Determine if there is water loss. b. Increase fluid intake or reduce sodium intake appropriately. c. Reduce insensible losses.

Question 46

What is the next step in managing hypernatremia?

Answer 46

Establish the underlying cause.

Question 47

How should chronic hypernatremia be corrected?

Answer 47

Over 24 hours. Avoid correcting too quickly to prevent the risk of cerebral edema.