HEAD(Station 1-10)
NECK(Station 1-10)
THORAX(Station 1-11)
ABDOMEN(Station 1-10)
UPPER LIMB (Station 1-10)
LOWER LIMB(Station 1-11)

NECK

OSCE
Station 6

The Parathyroid Glands

"
  • There are usually four parathyroid glands; two on each of the posterior surface of the right and left thyroid lobes.
  • These glands are usually divided into superior parathyroid glands and inferior parathyroid glands

 

"
"
  • The superior parathyroid glands are more constant in position compared to the inferior parathyroid glands.
  • The superior parathyroid glands usually lie at the level of the inferior border of the cricoid cartilage approximately 1 cm superior to the point of entry of the inferior thyroid artery into the thyroid gland.
  • The inferior parathyroid glands usually lie near the inferior pole of the thyroid gland or >1 cm below the entry of the inferior thyroid artery into the thyroid gland. Approximately 5% of inferior parathyroid glands can be found in other positions including within the thyroid gland itself or the mediastinum.

 

"
The superior parathyroid glands arise from the fourth pharyngeal pouch, and the inferior parathyroid glands arise from the third pharyngeal pouch.
The blood supply to the parathyroid glands is usually from branches of the inferior thyroid artery, which arises from the thyrocervical trunk from the first part of the subclavian artery.
"
  • The major function of the parathyroid glands is homeostasis of calcium metabolism.
  • The parathyroid glands secrete Parathyroid Hormone (PTH) which helps regulate serum calcium levels.
  • An increases in PTH levels causes increased absorption of calcium from the gut, increases calcium reabsorption from the kidney and increases osteoclasts activity to release calcium from bone into the blood.
  • PTH also plays a role in phosphate metabolism.
"
"Calcitonin is an important hormone in calcium haemostasis. A rise in calcium levels causes an increase in calcitonin which reduces the effect of PTH released by the parathyroid gland. The affects therefore cause a reduction in the amount of calcium absorbed by the gut and kidney and also inhibits osteoclast activity in the bone preventing bone reabsorption. However like PTH, calcitonin reduces the amount of phosphate reabsorbed by the kidney. "
"

  • Injury to the parathyroid glands can result in hypocalcaemia which clinically presents as:

    • Tingling and numbness of the perioral region and hands and feet
    • Tetany
    • Convulsions
    • Chvostek’s (tapping on the facial nerve causes twitching of facial muscles)

         and Trousseau’s sign muscular contraction following inflation of a sphygmomanometer cuff for several minutes) (both caused by neuromuscular excitability caused by hypocalcaemia).                                                      

     

"
"

  • Some causes of parathyroid gland enlargement include:

    • Parathyroid adenoma
    • Parathyroid hyperplasia
    • Parathyroid carcinoma

     

"
"

  • The investigations for parathyroid enlargement include:

    • Bloods: PTH, serum calcium, urea and electrolytes, vitamin D levels
    • Urine: calcium levels
    • USS neck
    • MRI scan
    • Bone density
    • Sestamibi parathyroid scintigraphy (MIBI scan)
"
"

  • The indications include:

    • Hypercalcaemia in all patients below 50 years
    • Hypercalcaemia greater than 3.00 mmol/l in all age groups
    • Symptomatic hypercalcaemia in all age groups
    • Deterioration in renal function
    • Progressive reduction in bone density
    • Excessive excretion of calcium in the urine
    • Any suspicion of malignant parathyroid disease.
"