management of Hyperparathyroidism_ surgical aspects - A lecture for the final year students delivered in 2024

The lecture on the surgical management of hyperparathyroidism is designed to equip final-year medical students with a comprehensive understanding of this endocrine disorder, focusing on the pathophysiology, clinical presentation, and particularly the surgical treatment options. Hyperparathyroidism is a condition characterized by excessive secretion of parathyroid hormone (PTH), which can lead to various complications such as hypercalcemia, kidney stones, osteoporosis, and neuromuscular symptoms. The lecture emphasizes the importance of early diagnosis and appropriate surgical intervention to prevent these complications and improve patient outcomes.

The session begins with an overview of the parathyroid glands, their anatomy, and their role in calcium homeostasis. The pathophysiology of hyperparathyroidism is explored, highlighting the differences between primary, secondary, and tertiary hyperparathyroidism. Primary hyperparathyroidism is most often caused by a benign adenoma in one of the parathyroid glands, while secondary hyperparathyroidism usually results from chronic kidney disease, and tertiary hyperparathyroidism can occur after prolonged secondary hyperparathyroidism, leading to autonomous PTH secretion.

The lecture then transitions to the clinical presentation of hyperparathyroidism. Students learn about the common signs and symptoms, including bone pain, muscle weakness, depression, fatigue, and gastrointestinal disturbances. The importance of a thorough history and physical examination is stressed, along with the role of laboratory tests in diagnosing hyperparathyroidism. Key diagnostic tools include serum calcium levels, PTH levels, and imaging studies such as neck ultrasound, Sestamibi scan, and 4D-CT, which help in localizing the overactive gland(s).

The core of the lecture focuses on the surgical management of hyperparathyroidism, which is the definitive treatment for primary hyperparathyroidism and certain cases of secondary and tertiary hyperparathyroidism. The main surgical approach discussed is parathyroidectomy, which involves the removal of the overactive parathyroid gland(s). The lecture covers the different types of parathyroidectomy, including minimally invasive parathyroidectomy (MIP), which is preferred for patients with a single adenoma that can be accurately localized preoperatively, and bilateral neck exploration, which is indicated in cases where multiple glands are suspected to be involved or localization studies are inconclusive.

Students are introduced to the preoperative workup for parathyroid surgery, which includes confirming the diagnosis, localizing the abnormal gland(s), and evaluating the patient’s overall health to ensure they are fit for surgery. The lecture emphasizes the importance of intraoperative PTH monitoring, which is used to confirm the successful removal of all hyperfunctioning parathyroid tissue during surgery. This technique involves measuring PTH levels before and after gland excision.

1. PARATHYOID – SURGICAL ASPECTS Ahmad Uzair Qureshi Module: 5. ENDOCRINE KING EDWARD MEDICAL UNIVERSITY, LAHORE 2O24

2. History 1850 First described by Sir Richard Owen in an Indian rhinoceros at the London Zoological Gardens in 1850. 1887 - “ G landulae parathyreoidae ’ - Sandström , Gley (1890) associated tetany following thyroid surgery 1 905, MacCallum found - relieve postoperative tetany by the injection of parathyroid extract. 1925 - first parathyroidectomy was performed by Mandl in Vienna.

3. Developmental Embryology of Parathyroid Glands Develop from the third and fourth pharyngeal pouches between the 5th and 12th weeks of gestation. Typical Characteristics: 30mg – four in Number - Color: Described as 'Portland brick ' (yellow/brown). Blood Supply: Both - inferior thyroidal artery. Location Variation: vary significantly

4. Inferior Parathyroid Glands: T hird pharyngeal pouch. located at the inferior pole of the thyroid gland (more than 50% of cases).

5. Superior Parathyroid Glands Embryonic Origin: Arise from the dorsal portion of the fourth pharyngeal pouch. Location Consistency: More constant - posterior aspect of the thyroid lobe in more than 80% of patients. Key Anatomical Reference: Situated in an area 2 cm in diameter, centered 1 cm around the junction of the inferior thyroid artery and the recurrent laryngeal nerve, near the cricothyroid junction.

6. PHPT “A n elevated total/ ionized, calcium in the presence of an inappropriately elevated or unsuppressed PTH.

7. ‘Bones, stones, abdominal groans and psychiatric Moans’. PRIMARY HYPERPARATHYROIDISM

8. Hypercalcaemia T/M of underlying aetiology + dietary modification.

9. Hypercalcaemia crisis Symptomatically with a total calcium of >3.5 mmol/L

10. Hypercalcemic crisis A cute Confusion, Abdominal Pain, Vomiting, Dehydration And Anuria. Prolong PR and Short QT Lethal Cardiac Arrhythmias. Where The Calcium Is >4.5 Mmol/L, Coma And Cardiac Arrest Can Occur.

11. Treatment I ncreasing renal excretion of calcium, R educe skeletal release of calcium T reat the underlying cause. Aggressive rehydration - 200–500 mL/h of normal saline U rine output >100 mL/h,

12. Once intravascular volume has been adequately restored, Loop diuretics, such as furosemide, E nhance the renal excretion of calcium.

13. Diagnosis A biochemical diagnosis. / Localization Positive imaging does not confirm the diagnosis, and negative findings cannot rule it out.

14. Localization studies In my opinion, the only localizing study required in a patient with untreated primary hyperparathyroidism is to localize an experienced parathyroid surgeon. John Doppman , 1986

15. Nuclear medicine-based studies (sestamibi scanning) Oxyphilic Cell concentration Mitochon drial uptake subtraction imaging and single-photon emission computed tomography (SPECT). False positives can be reduced by the addition of a thyroid-specifc radioactive tracer, such as 99 Tc-pertechnetate and subsequent subtraction images.

16. 4D-CT Scans

17. Parathyroid angiography and venous sampling for parathyroid hormone

18. Surgical management

19. The Miami criteria were developed to determine the extent of resection. A drop in the PTH into the normal range and to less than half the maximum preoperative PTH at 10 minutes appears to accurately predict single-gland disease

20. International Workshop on the Management of Asymptomatic Primary Hyperparathyroidism, a consortium of endocrinologists and endocrine surgeons, surgery is recommended for patients with: S erum calcium >1.0 mg/dL above the normal range; O steoporosis (bone mineral density with T-score <−2.5 at lumbar spine, total hip, femoral neck, or distal 1/3 radius); vertebral fracture; nephrolithiasis by x-ray, ultrasound, or CT; 24-hour urine calcium >400 mg/day and increased stone risk by biochemical stone risk analysis; or A ge <50.