2025 – PAGE 78 – 79 – ENDOCRINOLOGY

CALCIUM AND VITAMIN D RELATED DISORDERS

(DOUBLE TAKE) HYPERCALCEMIA

Hypercalcemia is defined as a calcium level > 12. Hypercalcemia shortens the ST segment; therefore it also shortens the QT interval. Polyuria occurs due to an osmotic diuresis. Patients can also get nausea, vomiting, a change in mentation, and possibly abdominal pain. Initial treatment for hypercalcemia should be IV HYDRATION. Possible etiologies include:

• ­FAMILIAL HYPOCALCIURIC HYPERCALCEMIA: The disorder is fairly benign, and there is nothing to do.
• ­WILLIAMS SYNDROME (AKA incorrectly as William’s Syndrome)
• ­VITAMIN D and VITAMIN A ingestion
• ­THIAZIDE DIURETICS
• ­SKELETAL DISORDERS: Including dysplasias, skeletal immobilization, and skeletal/body casting.
  • PEARL: For hypercalcemia due to immobilization, treat with IV fluids and loop diuretics
• ­HYPERPARATHYROIDISM
• ­MALIGNANCY
• ­MNEMONIC: “Bones, stones, abdominal groans and psychiatric moans.” This refers to the classic mnemonic used to describe the complications and associations with hypercalcemia.
  • BONES: Osteoporosis, osteomalacia, pathologic fractures, osteitis fibrosis cystica
  • STONES: Nephrolithiasis, nephrocalcinosis and arginine vasopressin resistance (previously nephrogenic diabetes insipidus).
  • ABDOMINAL GROANS: Nausea, vomiting, and constipation.
  • PSYCHIATRIC MOANS (or OVERTONES): Coma, delirium, depression, fatigue, and psychosis.

(DOUBLE TAKE) HYPOCALCEMIA

For hypocalcemia, look for a calcium level < 8.5 or an ionized calcium level < 4.5. Hypocalcemia is much less common than hypercalcemia but has much greater morbidity associated with it and is thus tested more often on the pediatric boards. Its effects can range from minimal symptoms due to mild hypocalcemia from hyperventilation to HORRIBLE outcomes. Symptoms of hypocalcemia include Paresthesias, Tetany, Carpopedal Spasm/Tetany (also known as Trousseau’s sign), Chvostek’s sign (abnormal reaction/tetany of the facial nerve when tapped), seizures that do not respond to benzodiazepines, laryngospasm (resulting in tachypnea—can look/sound like Croup), and prolonged QT.

• ­MNEMONIC: Calcium gluconate is given to stabilize the most important MUSCLE in the body, the HEART! If that’s something that you KNOW already, then it can help you remember that LOW calcium results in numerous “MUSCLE issues” in the body, potentially even CARDIAC.
• ­MNEMONIC: Most of us have had an anxious patient in the emergency room who complains of transient numbness and tingling in their hands and/or feet. It’s due to transient hypocalcemia from hyperventilation. If you can remember this association, you can remember that all of these tetany-like symptoms are related to hypOcalcemia!
• ­MNEMONIC: The CHvostek Sign (AKA CHvostek’s Sign) has to do with tapping the Cheek and looking for a twitch. CHeeky CHvostek sign! If all else failed with an anxious and hyperventilating patient, wouldn’t you want to slap their cheek?
• ­MNEMONIC: Carpopedal spasm due to hypocalcemia = Trousseau’s sign = “TROUSER’S” Sign = Think of it affecting the extremities!
• ­EARLY HYPOCALCEMIA: Refers to hypocalcemia within the first 3 days of life. Your differential should include asphyxia, IDM (Infant of a Diabetic Mother), maternal hyperparathyroidism, and IUGR.
• ­LATE HYPOCALCEMIA: Refers to hypocalcemia after 7 days, or during the 2nd week of life or later.
  • DIGEORGE/22Q11 DELETION
  • VITAMIN D DEFICIENCY
  • HYPOPARATHYROIDISM: Causes low calcium and high phosphorus. Can treat with calcitriol, which mimics PTH.
  • PSEUDOHYPOPARATHYROIDISM: Autosomal dominant disorder in which receptors are resistant to PTH. Serum PTH will be high. Calcium is low, phosphorus is high. Also look for brachydactyly (short and stubby fingers/toes), developmental delay, and moon facies.
  • HYPERPHOSPHATEMIA
  • LATE-STAGE CHRONIC KIDNEY DISEASE: Can’t hydroxylate Vitamin D to 1,25, so less calcium is absorbed.
  • NEPHROTIC SYNDROME: The low albumin causes the measured calcium to look low. Get an IONIZED calcium to confirm or calculate the corrected calcium by using the shortcut of adding 0.8 to the calcium level for every drop in albumin of 1 g/dL.
  • HYPOMAGNESEMIA: Be sure to CORRECT the magnesium!
  • ALKALOSIS: Shifts ionized calcium to the protein-bound form, resulting in less of the active form.
    • HYPERVENTILATION: Causes a transient respiratory ALKALOSIS, hypOcalcemia and paresthesias!
  • RHABDOMYOLYSIS: Initially there can be hypocalcemia. During the later recovery phase, there can actually be hypercalcemia. Calcium deposits into the muscles (let’s assume that’s the reason for the hypocalcemia).
  • ETHYLENE GLYCOL: Look for mention of calcium oxalate crystals in the urine.
    • MNEMONIC: Just assume that the calcium lost in the urine as calcium oxalate crystal causes the hypocalcemia.
    • (DOUBLE TAKE) CALCIUM OXALATE CRYSTALS: Calcium oxalatestones are the most common ones in humans. There are two types of calcium oxalate crystals. One is square and looks like it has an X on it. That one is very common. The other is elongated and looks like a rod. The long one is the one usually associated with ethylene glycol poisoning.

      IMAGE: www.pbrlinks.com/CALCIUMOXYLATE1

• • • MNEMONIC: calcium oXalate crystals look like a big X on a crystal.

      IMAGE: www.pbrlinks.com/CALCIUMOXYLATE2 (This one is related to ethylene glycol and kind of looks like a long can of beer or needles.)