MEDS12003 Lecture 3: SS week 3
Week 3: Parathyroids
Anatomy
• Paired
o Superior parathyroid gland
o Inferior parathyroid glands
Embryology
• During fetal development parathymus
descend with the thymus to the inferior
position
• Inferior more variable than superior pair
• Inferior are
usually found
near the posterior
aspect, lower
pole of the
thyroid
• 25% fail to cleave
from thymus
Ectopic Parathyroids
• Usually inferior pair
• Retrotracheal adenoma
o Superior glands –posterior to trachea
• Mediastinal adenoma
o Inferior glands –low in the neck,
anterosuperior mediastinum
• Intrathyroid –rare, either inferior or superior
• Carotid Sheath/undescended adenoma
o Rare, thought to be inferior
undescended glands
o Near Carotid bifurcation
Physiology
• Parathyroids secrete PTH (parathormone)
• Regulate serum calcium levels
• Calcitonin is effective in reducing the
osteoporotic progression in the elderly
• Serum calcium levels low
o PTH inc serum calcium by releasing
calcium from bone
o Inc calcium absorption in gut
o Dec renal calcium
1 | P a g e
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Primary Hyperparathyroidism
• Increased serum Calcium
• Most commonly females > 50 yo
• Increased parathormone PTH
• “Painful bones, renal stones, abdominal moans, psychic groans”.
o Caused by a single parathyroid adenoma in 80-90% of
cases o Multiple gland enlargement -hyperplasia10-20%
o Carcinoma <1%
Parathyroid adenomas
• Normal functioning parathyroids not visible on ultrasound
• Adenomas
o 5mm. L, 3mm. 1 mm. AP
• Homogeneous, ovoid
• Treatment
o Surgical excision
Shape
Sonography
• Enlargement
• Homogenous
• Vascular arc
• Hypoechoic to thyroid
2 | P a g e
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• Solid
• Rarely have internal calcification
• 0.8cm – 1.5cm
No effective definitive medical therapies are available for the treatment of primary hyperparathyroidism.
A typical finding described in parathyroid adenomas is a VASCULAR ARC which arises from thyroidal artery
branches – this may allow for differentiation from lymph nodes, which have a CENTRAL HILAR FLOW
PATTERN (left image)
Parathyroid adenomas
Carcinoma
• Rare cause of 10 hyperparathyroidism
• Usually larger than adenomas (>2cm)
• Often diagnosed at surgery
• Difficult to distinguish from adenomas
• Poor prognosis
False Positives
• Oesophagus –Lt lobe
• Lymph node
• Blood vessels
• Longus Colli muscle
• Thyroid nodules
3 | P a g e
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find more resources at oneclass.com
Document Summary
Embryology: during fetal development parathymus descend with the thymus to the inferior position. Inferior are usually found near the posterior aspect, lower pole of the thyroid: 25% fail to cleave from thymus. Ectopic parathyroids: usually inferior pair, retrotracheal adenoma, superior glands posterior to trachea, mediastinal adenoma. Inferior glands low in the neck, anterosuperior mediastinum. Intrathyroid rare, either inferior or superior: carotid sheath/undescended adenoma, rare, thought to be inferior undescended glands, near carotid bifurcation. Increased serum calcium: most commonly females > 50 yo. Painful bones, renal stones, abdominal moans, psychic groans : caused by a single parathyroid adenoma in 80-90% of cases o multiple gland enlargement -hyperplasia10-20, carcinoma <1% Parathyroid adenomas: normal functioning parathyroids not visible on ultrasound, adenomas, 5mm. Sonography: enlargement, homogenous, vascular arc, hypoechoic to thyroid. 2 | p a g e: solid, rarely have internal calcification, 0. 8cm 1. 5cm. No effective definitive medical therapies are available for the treatment of primary hyperparathyroidism.
