2. Anatomy
• Discovered by Ivar Sandstrom in 1880
• 4 glands (80-87%), 1-12 glands
• Oval, resilient, dull yellow-brown @ 4 × 3 × 1.5 mm
• @ 35-40mg (10-78mg)
• Upper pair really derives from the fourth branchial
cleft, located in middle third of the posterolateral
border of the thyroid gland
• Lower pair from the third branchial cleft, close to the
lower pole of the thyroid gland, near the inferior
thyroid artery
• >> symmetric distribution
Fletcher CDM. Diagnostic histopathology of tumors. 2021
Bonnie J. The parathyroid, glands. Diagnostic ultrasound. 2018
3. Embriology of the parathyroid gland
Policeni BA, et al. Anatomy and embryology of the thyroid and parathyroid glands. 2012
4. Blood Supply
• >> supplied by a single
dominant artery (80%)
• The vascular supply of
the upper & lower
parathyroid glands
comes from branches of
the inferior thyroid
arteries
• 20% upper parathyroid
gland solely by superior
thyroid artery
Flint BW, et al. Cumming’s otolaryngology. Head and neck surgery. 2015
8. Physiology
• Parathyroid glands (>> chief cells) secrete PTH
• PTH : ↑ serum calcium (ca)
– Kidney : ↑ ca reabsorption
– Bone : release stored calcium in bones into the ECF
– Intestines : ↑ gut ca absorption (indirectly)
• Ionized calcium : muscle contraction, secretion of
neurotransmitters & hormones, coagulation
pathways
• Ionized serum ca 4.65 - 5.25 mg/dL
• Total serum ca 8.5 - 10.5 mg/dL
Fletcher CDM. Diagnostic histopathology of tumors. 2021
Thakker. The parathyroid, hypercalcemia and hypocalcemia. Goldman-cecil medicine. 2020
9. • Parathyroid cells express a G protein–coupled
receptor (GPCR), referred to as the calcium-
sensing receptor (CaSR), that detects changes
in extracellular calcium & leads to alterations
in PTH secretions
Thakker. The parathyroid, hypercalcemia and hypocalcemia. Goldman-cecil medicine. 2020
10. Parathyroid hormone (PTH)
• PTH : 84–amino acid peptide
• PTH gene (chromosome 11p15)
• PTH shares a receptor with PTH-related
peptide (PTHrP)
• PTH/PTHrP receptors are expressed in kidney,
bone & intestinal cells
Thakker. The parathyroid, hypercalcemia and hypocalcemia. Goldman-cecil medicine. 2020
11. Regulation of extracellular fluid (ECF) calcium (Ca2+) by parathyroid hormone
(PTH) action on kidney, bone, and intestine.
Thakker. The parathyroid, hypercalcemia and hypocalcemia. Goldman-cecil medicine. 2020
12. Introduction
• Postop hypocalcemia : >> complication of total
thyroidectomy (TT)
• Incidence 30 - 60% (1.6-50%)
• >> resolved in < 6 months
• Permanent hypoparathyroidism:
– >> long-term complication after TT
– Rarely fatal
– Significant morbidity
– Increased costs
Dedivitis RA, et al. Hypoparathyroidism after thyroidectomy: prevention, assessment and management. 2017
Albuja-cruz MB, et al. A ‘‘safe and effective’’ protocol for management of post-thyroidectomy hypocalcemia. 2015
13. Introduction
• Hypocalcemia : calcium level < 8.0 mg/dl
• Permanent hypocalcemia : insufficient PTH
levels to maintain normal calcemia 6 mo after
surgery, however, recovery may take more
than 12 mo
• Recovery of parathyroid gland function : PTH
levels are above 10 pg/ml & no require daily
calcitriol & calcium supplementation to avoid
symptoms of hypocalcemia
Dedivitis RA, et al. Hypoparathyroidism after thyroidectomy: prevention, assessment and management. 2017
14. • The median incidence:
– Transient hypocalcemia 27% (19%–38%)
– Permanent hypocalcemia 1% (0%–3%)
• It is prone to occur after TT or during a
reoperation for thyroid diseases (15-30%)
• Hypoparathyroidism occurs:
– After direct injury
– Devascularization
– Obstruction of venous drainage
– Inadvertent excision of the parathyroid glands
• Acute symptoms : perioral paresthesia, tingling in
the hands & legs, anxiety
Dedivitis RA, et al. Hypoparathyroidism after thyroidectomy: prevention, assessment and management. 2017
16. Prevention
• Anatomic knowledge & surgical experience are
essential
• The parathyroid glands & their vascularization should
be identified in situ, carefully manipulated & preserved
• Autotransplantation is indicated in case of incidental
removal.
• Dexamethasone 8 mg iv, 45-90 minutes before skin
incision
– Not yet a standard
– Reduce the rate of transient hypoparathyroidism &
laryngeal nerve palsy
Dedivitis RA, et al. Hypoparathyroidism after thyroidectomy: prevention, assessment and management. 2017
Sack BC, et al.Postoperative hypoparathyroidism – definitions and management. 2015
Kolahdouzan M, et al. Preventive Effect of Dexamethasone Therapy on the Transient Hypoparathyroidism through Total Thyroidectomy . 2019
17. • PTH levels declined to 41.9% of its initial value
on the first day after op
• PTH was correlated positively with calcium &
inversely with phosphate from POD 1–14
• PTH threshold of <7 ng/L on POD 1 was
predictive of persistent hypoparathyroidism
Dedivitis RA, et al. Hypoparathyroidism after thyroidectomy: prevention, assessment and management. 2017
18. • Increased the risk of permanent
hypoparathyroidism:
– Thyroiditis
– Iatrogenic removal (20%)
– Injury of parathyroid glands and/or damage of
their blood supply during thyroidectomy
– Failed autotransplantation
Dedivitis RA, et al. Hypoparathyroidism after thyroidectomy: prevention, assessment and management. 2017
19. Predictors of permanent hypocalcemia
• Total thyroidectomy
• Central neck dissection
• Surgery for recurrent goitre
• Reoperation for bleeding
• Ca < 1.88 mmol/l at 24 h after surgery
• Identification < 2 parathyroid glands at surgery
• Graves’ disease
• PTH ≤6.6 pg/ml the day after surgery
• Parathyroid tissue on the final pathology report
Dedivitis RA, et al. Hypoparathyroidism after thyroidectomy: prevention, assessment and management. 2017
Mejia MG, et al. Hypocalcemia posthyroidectomy: prevention, diagnosisand management. 2018
20. Management
• The aim : preserve serum calcium in the low
normal or mildly subnormal levels
• Rapid identification aims to
– Prevent the resulting clinical symptoms
– Reduce hospital stay
– Reduce the cost of the process
• For patients with symptoms of hypocalcemia,
which is considered an emergency, or
corrected serum calcium ≤7.5 mg/dl
Dedivitis RA, et al. Hypoparathyroidism after thyroidectomy: prevention, assessment and management. 2017
21. Management
• Acute hypocalcemia :
– Oral calcium (Ca carbonate) 1-3g in 3-4 doses, or
– Iv infusion of 10% ca gluconate (2g over 2h), check 6-8hr
• Severe symptoms:
• Iv infusion of 10% ca gluconate 20ml in 5% dextrose 100ml in 20
minutes
• Iv ca intake should be maintained
• Oral ca carbonate 1–1.5 g every 24 h
• Calcemia control at 4–6 h
• Ca levels > 7.5 mg/dl & asymptomatic, oral ca maintained & serum ca
monitored at 24 h
• Ca levels < 7.0 mg/dl, 100 ml ca gluconate in 900 ml of D5 (0.5–2
mg/kg/h), checks/6 h (maintain Ca 8 - 9 mg/dl)
Dedivitis RA, et al. Hypoparathyroidism after thyroidectomy: prevention, assessment and management. 2017
22. Management
• If refractory:
– Check Mg : if low, treated
– Oral ca supplementation
– Oral calcitriol 0.25ug/day (0.125-4ug/day)
– Hydrochlorothiazide (12.5-50 mg daily)
• Recombinant PTH 50ug/day (25-100ug/day), sc
– Can’t be controlled with calcium & calcitriol
– Maintains normocalcemia
– Reduction of vit D & ca supplements dosage
– Lessen risk of ca deposition in kidneys
Dedivitis RA, et al. Hypoparathyroidism after thyroidectomy: prevention, assessment and management. 2017
Sack BC, et al.Postoperative hypoparathyroidism – definitions and management. 2015
23. Post-thyroidectomy hypocalcemia protocol
Albuja-cruz MB, et al. A ‘‘safe and effective’’ protocol for management of post-thyroidectomy hypocalcemia. 2015
Sensitivity 85%
NPV 92%
High risk 37%
Inter risk 13%
Low risk 50%
24. Albuja-cruz MB, et al. A ‘‘safe and effective’’ protocol for management of post-thyroidectomy hypocalcemia. 2015
25. Albuja-cruz MB, et al. A ‘‘safe and effective’’ protocol for management of post-thyroidectomy hypocalcemia. 2015
