24.3 Hyperparathyroidism

Question 1

a) List the causes of primary hyperparathyroidism. (10%)

Answer 1

> > Parathyroid adenoma.

> > Gland hyperplasia.

> > Parathyroid cancer.

Question 2

b) Which biochemical abnormalities are seen in primary hyperparathyroidism? (15%)

Answer 2

> > Elevated parathyroid hormone.

> > Elevated calcium.

> > Reduced phosphate.

> > Elevated alkaline phosphatase.

Question 3

c) What are the systemic effects of hyperparathyroidism? (20%)

Answer 3

1. Renal:
   stones,
   impaired concentrating ability,
   polyuria,
   renal failure.
2. Skeletal:
   bone resorption,
   pain,
   fractures,
   osteitis fibrosis cystica.
3. Gastrointestinal:
   calcium-induced gastric hypersecretion,
   peptic ulceration,
   acute and chronic pancreatitis,
   nonspecific abdominal pain.
4. Central nervous system:
   nonspecific symptoms,
   weakness,
   deterioration in memory and cerebration.
5. Cardiovascular:
   conduction defects, hypertension.

Question 4

d) What important factors must the anaesthetist consider before, during and after anaesthesia for
parathyroidectomy? (55%)

Answer 4

Preoperative:
» Consider underlying cause
and associated issues:
coexistent endocrine disease,
chronic kidney disease,
recent transplant.

> > Consider the impact of hyperparathyroidism:
calcium level
(may need correction preoperatively,
pamidronate and fluids),

renal function,
cardiac rhythm (check ECG).

Intraoperative:

> > Anaesthesia: surgical field near airway.
Reinforced tube or LMA.

Can be performed with
regional anaesthetic technique;
bilateral superficial cervical plexus
blocks with supplementation.

> > Position:
supine, head-up tilt,
sandbag under shoulders,
head ring.
Care with positioning;
risk of osteoporosis and
pathological fractures.

> > Warming: potentially long surgery
especially if checking with frozen
sections for completeness of
adenoma resection or on-table parathyroid
hormone assays.

> > Methylene Blue to identify glands:
risk of anaphylaxis,
interference with
oxygen saturations monitoring.

> > Recurrent laryngeal nerve monitoring:
short-acting muscle relaxant for intubation.
Consider remifentanil infusion thereafter.`

Postoperative:
» Hypocalcaemia:
check at 6 hours and 24 hours.
May need oral or intravenous supplementation.

> > Recurrent laryngeal nerve palsy:
voice change, difficulty breathing.

> > Incomplete resection.

> > Analgesia:
requirements low with local
anaesthetic use. NSAIDs may be
contraindicated due to comorbidities.

Question 5

Parathyroid gland anatomy

Answer 5

There are four parathyroid glands,
located at the poles of the thyroid gland.

However, there is great variation in their location.

They are small, 3 × 6 × 2 mm.

Blood supply is from the inferior thyroid artery.

Their secretion is inhibited by
high parathyroid hormone and
calcium levels and stimulated by
high phosphate levels

Question 6

Secondary hyper PTH

Answer 6

Secondary hyperparathyroidism occurs in
chronic kidney disease:

the failing kidney does not excrete
phosphate efficiently and
does not hydroxylate vitamin D,

reducing calcium absorption
from the gastrointestinal tract.

After a prolonged period of
secondary hyperparathyroidism,

tertiary hyperparathyroidism may develop.

Here, even once calcium and phosphate
levels return to normal (for example after a renal transplant), the parathyroid
glands continue to oversecrete.