Parathyroid disease

• The Parathyroid gland regulates the serum concentration of ionized calcium.  

Hyperparathyroidism

three types of Hyperparathyroidism

1. primary
   1. Parathyroid hyperplasia due to :
      1. parathyroid adenomas/maligancy
      2. MEN 1, MEN2
2. secondary – Hyperplasia that is secondary to another disease process
   1. Vitamin D deficiency
   2. weight loss surgery
   3. Celiac or Crohn’s Disease
   4. Chronic kidney disease

[CKD → impaired renal phosphate excretion → ↑ phosphate blood levels→  ↑ PTH secretion]

[CKD → ↓ biosynthesis of active vitamin D → ↓ intestinal calcium resorption and ↓ renal calcium reabsorption → hypocalcemia → ↑ PTH secretion]

3. tertiary
   1. results from untreated secondary HPT with continuously elevated PTH levels, even if the original stimulus is removed 
4. Renal disease
   1. secondary or tertiary hyperparathyroidism → renal osteodystrophy → bone lesions

Other: 

• Lithium therapy
• Ectopic PTH secretion from non-parathyroid malignancy

Presentation

• The classic signs and symptoms of hyperparathyroidism are usually seen late in the disease process.  
• When calcium levels are >12mg/dL patients are usually symptomatic and will present with:
  • Stones – kidney stones, hematirua
  • Bones – Bone, muscle, and joint pain, Pseudogout
  • Abdominal groans – Lack of appetite → weight loss, Nausea, constipation, Gastric or duodenal ulcers, Acute pancreatitis
  • Psychic moans – depression, fatigue, anxiety, sleep disorders

Hypoparathyroidism (failing parathyroid function or frank hypoparathyroidism)

• Post thyroid surgery or radiation
• Autoimmune endocrine disease
• Severe hypomagnesaemia (see in alcoholics and in cases of really bad malabsorption due to another disease process)

Investigations

	Calcium	Phosphate	ALP	PTH
Primary	Blood: high Urine:  Hypercalciuria (Ca/Cr > 0.02)	low	HIGH	HIGH
Secondary	Normal or Low	Normal or high (in CKD) Low (in most other causes)	HIGH	HIGH
Tertiary	HIGH	HIGH	HIGH	Very HIGH