Sketchy Path: Renal - "Calcium Disorders"

Question 1

Calcium in the blood comes in three forms: _________________.

Answer 1

free, bound to albumin, and bound to phosphate (like the PHOSter Pharms calcium, the photo ALBUM of cows, and the FREE range cows)

Question 2

The metabolically active form of calcium is which kind?

Answer 2

Free

Question 3

What formula can help correct erroneous calcium?

Answer 3

(4 –albumin) • 0.8 + measured total calcium

Low albumin can make the levels of calcium erroneously low.

Question 4

How does acidosis affect calcium?

Answer 4

Acidosis causes albumin to release calcium (like the cow jumping over the acid-leaking pipe). This can result in symptoms of hypercalcemia even with a normal measured total calcium.

This happens because albumin takes up H+ to buffer the blood. When it does this, it releases Ca.

Question 5

The normal range for calcium is _______.

Answer 5

8.5 - 10.2

Question 6

The most common cause of hypocalcemia is _______________.

Answer 6

hypoparathyroidism (like the cow kicking over the PHd on tour)

Question 7

Hypoparathyroidism presents with what lab findings?

Answer 7

• Low calcium (falling bucket of milk)

* High phosphate (like the Phoster hat sailing through the air)

Question 8

Explain Albright hereditary osteodystrophy.

Answer 8

• Autosomal dominant disorder (DOMINo phone case)
• Affects G proteins that mediate PTH signaling (G headphones)
• PTH cannot have its effect, so levels of PTH are high but it is like they are low (PHd is waving her arms frantically but it is not doing anything)
• Leads to low Ca and high Phos (like spilled milk and high hat)
• Inherited from mother only due to imprinting (mom watching in horror)
• Hypoplasia of the fourth and fifth metacarpals (kid getting kicked has these two fingers flexed)

Question 9

By what three ways does CKD lead to hypocalcemia?

Answer 9

• Decreased synthesis of vitamin D
• Retention of phosphate leads to increased release of PTH
• Rising phosphate levels bind to serum calcium and reduce the metabolically active form

Question 10

List three transfusion products that can cause hypocalcemia.

Answer 10

• Phosphate
• Citrate
• Albumin

All are found in blood products.

(Guy wearing Phosphate hat standing on CITRus crate with photo ALBUM.)

Question 11

These four medications can all cause hypocalcemia: _________________.

Answer 11

foscarnet, loop diuretics, cinacalcet, and bisphosphonates

Question 12

Rarely, severe ______________ can cause hypocalcemia through fat necrosis.

Answer 12

pancreatitis

Think of the guy with the pancreas sponge getting kicked by the cow –he has a skull on his shirt.

Question 13

95% of cases of hypercalcemia are caused by ________________.

Answer 13

hyperparathyroidism (like the woman with the large bowtie and four large lapels)

Question 14

____________ tends to be more severe than hyperparathyroidism.

Answer 14

Hypercalcemia of malignancy

Question 15

PTHrp is most commonly associated with ______________.

Answer 15

squamous cell carcinoma of the lung and renal cell carcinoma

Question 16

True or false: those with hypercalcemia of malignancy typically have lytic bone lesions.

Answer 16

True

Unlike hyperparathyroidism, those with hypercalcemia of malignancy typically have lytic lesions (like the scooped bone ice cream sundae next to the girl pretending to be a PHd).

Question 17

By what other mechanism does cancer cause hypercalcemia (that is, other than PTHrp)?

Answer 17

Osteolytic bone lesions, most commonly seen in breast cancer and multiple myeloma (like the girl EATING the ice cream with the archer and the breast bibs)

Question 18

What is the mechanism of familial hypocalciuric hypercalcemia?

Answer 18

• Inability to sense calcium in the nephron leads to excess absorption (kidney glasses with the “New Sensation” sign)
• Autosomal dominant (like the DOMINo pattern around the border of the Family Creamery sign)

Question 19

How can you diagnose familial hypocalciuric hypercalcemia?

Answer 19

Urinary calcium excretion showing low Ca

Think of the sLOW chURN on the Family Creamery sign.

Question 20

List two causes of hypercalcemia other than malignancy or hyperparathyroidism.

Answer 20

• Thiazide use (like the kid with pale thighs)
• High levels of vitamin D either from granulomatous disease or ingestion (like the robot holding the soccer ball and the Milk Alkali cookies)