4. Clinical anatomy of PT gland
The parathyroid gland is four glands organ, hence, the surgeries
are complicated due to their variable locations.
Goal of surgery usually is to remove just the diseased glands.
Anatomy & Embryology
Parathyroid glands are 2 pairs of glands
which found on the posterior part of the
lateral lobes of the Thyroid gland.
They are developed from: endodermal
proliferation
of the 3rd and 4th pharyngeal pouches.
Light yellowish to
reddish color, oval
shaped.
Normal glands are usually
approximately 5 by 4 by 2
millimeters in size and weigh
35 to 50 milligrams
84% of the people
have 4
glands, 13% have
more than 4
glands, and very
small amount have
3 glands
5. Clinical anatomy of PT gland
Inferior parathyroid gland
Derived from the dorsal aspect of 3rd
pouch. They migrate inferiorly along with
the development of the thymus.
They reach normal position at week 7.
From the dorsal aspect of 4th pouch. They
migrate caudally and medially. They reach
normal position at week 5- usually at
cricothyroid junction. From the 4th pouch
also thyroid gland is derived.
Superior parathyroid gland
6.
7. Clinical anatomy of PT gland
The inferior glands have longer migration
pass w/ the thymus, hence, their positions
are more variable compare to the upper
glands.
Locations inferior parathyroid glands
They can be found as high as in the neck as the carotid
Sheath found, anterior mediastinum, or even the
pericardium.
However, the majority of inferior parathyroid glands are
found in the inferior poles of thyroid gland.
8. Clinical anatomy of PT gland
These glands are closely associated with the
lateral lobes of the thyroid and have a short line
of embryologic descent.
Will be found behind the middle the of
thyroid gland.
Locations Superior parathyroid glands
10. Arterial supply
• Inferior parathyroid are supplied by the
inferior thyroid artery *
• The superior parathyroid is supplied by the
inferior thyroid artery as well, by an
anastomosis between inferior and superior
thyroid artery**.
Superior and inferior parathyroid glands
*In case of absence of
inferior thyroid artery they
are supplied by the superior
thyroid artery.
Derived from
thoracocervical artery
**Derived from external
carotid artery
11. Venous drainage
Superior and inferior parathyroid glands
Venous
drainage
into superior,
inferior and
middle thyroid
veins.
12. Lymphatic drainage
Superior and inferior parathyroid glands
The lymphatic vessels of
the parathyroid glands
drain (along with those of
the thyroid gland) into the
deep cervical lymph nodes
and paratracheal lymph
nodes.
13. Innervation
Superior and inferior parathyroid glands
Supplied by Sympathetic nervous system.
Superior and cervical (thyroid branches)
sympathetic ganglia.
It is important to note that these nerves are
vasomotor, not secretomotor – endocrine secretion
of parathyroid hormone is controlled hormonally.
17. Phosphate regulation
Concentration of serum phosphate depends on the function of
parathyroid glands and the kidney (both glomerular filtration and
tubular reabsorption).
Parathyroid hormone decreases renal reabsorption of
phosphate. Renal insufficiency in general results in elevation of serum
phosphate.
Usually phosphate and calcium have inverted relationship, except for
Vitamin D overdose, in which both are increased.
22. Secondary hyperparathyroidism
Secondary hyperplasia due to decrease in Calcium absorption or increase
In phosphorous.
• Decrease intake of vitamin D
• Chronic renal failure (unable to clean phosphorus and to make vit D)
Causes:
Labs: increase ALP, increase PTH, hypocalcemia, hyperphosphataemia
23. Tertiary hyperparathyroidism
Occurs after prolonged secondary hyperparathyroidism, causing glands
to act autonomously having undergone hyperplastic or adenomatous change.
This causes Ca2+ increase from increased secretion of PTH unlimited by feedback
control. Seen in chronic renal failure.
Causes:
24. Malignant hyperparathyroidism
Parathyroid-related protein (PTHrP) is produced by some
squamous cell lung cancers, breast and renal cell carcinomas.
This mimics PTH resulting in Ca2+ increase.
(PTH is decreased, as PTHrP is not detected
in the assay).
Causes:
25. Labs & Tests
Blood tests - Calcium level, PTH level, PO43– decrease (unless in renal failure),
ALP increased Bone activity
Bone assessment- Imaging- rarely we can see osteitis fibrosa cystica.
Bone Density tests- Dual-energy x-ray absorptiometry (DXA) testing is the most c
ommonly used method for measuring bone density. Vertebral imaging due to
asymptomatic vertebrae fractures.
Kidney assessment- , 24 hours urinary calcium (kidney stones), creatinine,
27. Primary hypoparathyroidism
PTH secretion is decreased due to failure of the gland. Due to injury to the gland or
its blood vessels (iatrogenic), autoimmune destruction or Digeorge syndrome.
Presentations:
Hypocalcemia signs: mild- cramps, perioral numbness/paraesthesia. Severe- Trous
seau’s sign, laryngospasm, seizures etc.
Chvostek’s sign positive
Trousseau’s sign positive
28. Secondary hypoparathyroidism
PTH secretion is decreased due to hypomagnesemia, radiation, surgery.
Presentations:
Hypocalcemia signs: mild- cramps, perioral numbness/paraesthesia. Severe- Trous
seau’s sign, laryngospasm, seizures etc.
Chvostek’s sign positive
Trousseau’s sign positive
29. Pseudohypoparathyroidism type 1A
Autosomal dominant, inherited from the mother (imprinting). It is expressed by end
organ resistance of kidney or bone to PTH.
Presentations:
Unresponsiveness kidney hypocalcemia despite PTH increase.
Constellation of physical findings (Albright hereditary osteodystrophy):
• Short digits 4th and 5th
• Short stature
• Obesity
• Developmental delay
Labs: Ca decreased, PTH increased, ALP stable/increased
32. Parathyroidectomy indications
PHPT- surgery is indicated in any symptomatic patient
• Polydipsia and polyuria.
• Nephrolithiasis or nephrocalcinosis.
• Hypercalcuria (24-hour urine calcium level >400 mg/dL).
• Impaired renal function (glomerular filtration rate [GFR] <60 mL/minute).
• Osteoporosis (bone density score <-2.5), fragility fracture, or vertebral compressio
n fracture.
• Pancreatitis, peptic ulcer disease, or gastroesophageal reflux.
• Neurocognitive dysfunction or neuropsychiatric symptoms attributable to PHPT.
33. Parathyroidectomy indications
PHPT- asymptomatic patients indications:
• Age <50 yrs
• Serum calcium level >1 mg/dL above normal range.
• Silent nephrolithiasis
• Patients with high risk for cardiovascular disease
• patients with clinical features such as muscle weakness, decreasing functional
capacity, abnormal sleep patterns, and fibromyalgia may also be considered for
parathyroidectomy
Parathyroid cancer: although it’s rare cause for PHPT, when there is a suspicion for
Cancer, parathyroidectomy is indicated. Elevated serum calcium level, elevated PTH,
with palpable or painful neck mass.
Parathyroid crisis
34. Contraindications
• Contralateral recurrent laryngeal nerve (RLN) injury o
r vocal cord dysfunction is a relative contraindication to
neck exploration for parathyroidectomy, because bilater
al RLN injury can be life-threatening.
• Symptomatic cervical disc disease because of the mil
d neck extension necessary in positioning patients for th
yroid and parathyroid surgery. Hyperextension may
potentially cause spinal cord injury in patients with
cervical disc disease.
• Familial hypocalciuric hypercalcemia (FHH) is an absolu
te contraindication to parathyroid surgery. These patient
s do not have PHPT, and surgical intervention does not r
esult in cure.
Parathyroid glands originating more cranially in third branchial pouch migrate in close association with thymus to reach final position more caudally with respect to parathyroid glands originating in fourth branchial pouch.
In secondary hyperparathyroidism, a disease outside of the parathyroids causes all of the parathyroid glands to become enlarged and hyperactive. It is usually caused by kidney failure, a problem where the kidney is unable to clean the blood of phosphorus produced by the body and unable to make enough vitamin D (specifically calcitriol, the active form of vitamin D). The build-up of phosphorous leads to low levels of calcium in the blood, which in turn stimulates the parathyroid glands to increase parathyroid hormone (PTH) production which in turn causes them to grow
Chvostek’s sign- tapping of facial nerve – contraction of facial muscles.
Trousseau sign- occlusion of brachial artery with BP cuff- carpal spasm.
Mg is required for the secretion of PTH
Imprinting gene expression by only one allele- we inherit only one working copy. Depending on the gene, either the copy from mom or the copy from dad is epigenetically silenced. Silencing usually happens through the addition of methyl groups during egg or sperm formation.
is an inherited condition that can cause hypercalcemia, a serum calcium level typically above 10.2 mg/dL. It is also known as familial benign hypocalciuric hypercalcemia (FBHH) where there is usually a family history of hypercalcemia which is mild, a urine calcium to creatinine ratio <0.01, and urine calcium <200 mg/day.
