PANCE Blueprint Endocrinology (6%)

Hypoparathyroidism

Patient will present as → a 39-year-old woman after total thyroidectomy for papillary carcinoma of the thyroid is noted to have carpal spasm when her blood pressure is taken and facial muscle contractions with tapping over the facial nerve. You also note increased deep tendon reflexes along with perioral paresthesia. Lab work reveals a decreased serum calcium, decreased parathyroid hormone, and an elevated serum phosphate. On EKG there is a prolongation of the QT interval

Hypoparathyroidism will present with a decreased parathyroid hormone (↓ PTH)

  • Hypoparathyroidism is rare, you are much more likely to be tested on hyperparathyroidism
  • Two most common etiologies are postsurgical (damage from neck or thyroid surgery) or autoimmune
    1. Accidental damage/removal of parathyroid during neck/thyroid surgery
    2. Autoimmune destruction of the thyroid gland

Patients will show signs of neuromuscular irritability with carpopedal spasm, laryngeal spasm,  tingling, tetany, and facial grimacing.

Diagnosis is made by triad: ↓ Ca+ ↓ PTH ↑ phosphate

  • EKG = Prolonged QT
  • Why the low serum calcium? Calcium is low because the gland cannot secrete PTH (hence a low PTH) and PTH is responsible for the reabsorption of calcium from the bones, kidneys and GI tract. Because you can't reabsorb Calcium, your calcium will be low.
  • This is easy to remember: Hyo-parathyroid literally causes a LOW PARATHYROID HORMONE. If you know that PTH is responsible for calcium reabsorption, you will know that CA+ will be low as well.

The following are signs of hypocalcemia:

  • Chvostek's sign (watch video) is the twitching of the facial muscles in response to tapping over the area of the facial nerve.
  • Trousseau's sign (watch video) is carpopedal spasm caused by inflating the blood-pressure cuff to a level above systolic pressure for 3 minutes.
  • ↑ DTRs and carpopedal spasms
Serum Ca
Serum Phos
PTH
Common Cause
Hyperparathyroidism
adenoma
Hypoparathyroidism
parathyroidectomy
Ectopic PTH
malignancy
Vit D malabsorption
celiac disease, other GI disease
↓ D with no phosphate excretion from the kidney.
renal failure, pseudo hypoparathyroidism

Treatment: Vitamin D and Calcium

  • Tetany- secure airway, IV calcium gluconate
ppt-on-hypoparathyroidism-akki-8-638

Chvostek's sign is seen in patients with hypocalcemia secondary to low PTH secretion

hypoparathyroidism_5089_1470263469 An uncommon condition characterized by a low level of parathyroid hormone (PTH). Often caused by “accidental” removal of the parathyroid glands during thyroid surgery. Other causes of parathyroid deficiency include tumors and heavy metal poisoning. Treatment consists of taking supplements to normalize calcium and phosphorus levels.

Hypoparathyroidism Picmonic

parathyroid-gland_5110_1472585798 The parathyroid gland is a series of four small glands located in the neck on the rear surface of the thyroid gland. It serves primarily in calcium homeostasis and has a blood calcium sensor that detects when blood calcium levels are abnormally low. It responds by releasing parathyroid hormone (PTH) which stimulates osteoclasts into action. Osteoclasts resorb bone and release a large amount of calcium. This calcium enters the blood and results in increased blood calcium levels. PTH can also activate vitamin D by promoting the activity of an enzyme that converts inactive vitamin D to active vitamin D

Parathyroid Gland Overview Picmonic

Question 1
A 65-year-old woman with a seizure disorder controlled with phenytoin presents to your office complaining of muscle cramps, dry skin, and depression. Examination shows carpal-pedal spasms after application of a blood pressure cuff. The most likely diagnosis is  
A
Hypothyroidism
B
Hyperventilation with panic attacks
C
Hyperkalemia
D
Hypocalcemia
E
Hyponatremia
Question 1 Explanation: 
Hypocalcemia is defined as a decrease in total plasma calcium concentration < 8.8 mg per dL in the presence of normal plasma protein concentration. Causes include hypoparathyroidism, vitamin D deficiency, renal tubular disease, magnesium depletion, acute pancreatitis, hypoproteinemia, septic shock, hyperphosphatemia, and drugs, including phenytoin, phenobarbital, and rifampin. Most patients are asymptomatic. Symptoms, when present, include muscle cramps involving the legs and back, mental status changes, dry skin, depression, and psychosis. Papilledema may occasionally occur, and cataracts may develop after prolonged hypocalcemia. Severe hypocalcemia (< 7 mg per dL) may cause tetany, laryngospasm, or generalized seizures. With hypocalcemia giving rise to latent tetany, the patient may exhibit a positive Chvostek’s sign (involuntary twitching of the facial muscles caused by a light tapping of the facial nerve just anterior to the exterior auditory meatus) or a positive Trousseau’s sign (carpopedal spasm caused by reduction of the blood supply to the hand with a blood pressure cuff inflated to 20 mm Hg above the systolic BP applied to the forearm after 3 minutes). Hypocalcemia can cause heart block and arrhythmias. ECG changes show prolongation of the QTc and ST intervals. T-wave peaking or inversion can also occur. Severe hypocalcemic tetany is treated initially with intravenous infusion of calcium salts (calcium gluconate). In chronic hypocalcemia, oral calcium and vitamin D supplements are usually sufficient. Treatment of hypocalcemia in patients with renal failure must be combined with dietary phosphate restriction and phosphate-binding agents such as calcium carbonate to prevent hyperphosphatemia and metastatic calcification.
There is 1 question to complete.
Return
Shaded items are complete.
1
Return
Hyperparathyroidism (Prev Lesson)
(Next Lesson) Hyperthyroidism (ReelDx)
Back to PANCE Blueprint Endocrinology (6%)

The Daily PANCE and PANRE

Get 60 days of PANCE and PANRE Multiple Choice Board Review Questions delivered daily to your inbox. It's 100% FREE and 100% Awesome!

You have Successfully Subscribed!