Electrolyte Disorders

Question 1

Which of the following electrolyte abnormalities is most likely to be responsible for this patient’s presentation?

Answer 1

This patient’s ECG is remarkable for tall, “peaked” T-waves in the anterior and lateral precordial leads (V3-V6). Tall T-waves are a typical ECG finding in hyperkalemia and can occur with serum potassium greater than 5.5 mEq/L (normal 3.5-5).

Question 2

How Abnormal levels of magnesium can affect both potassium and calcium. . Magnesium is required for the proper functioning of this protein. .

Answer 2

For calcium, severe magnesium depletion can result in improper functioning of the CaSR (calcium-sensing receptor) channel, a membrane protein receptor on the surface of chief cells in the parathyroid gland.

Question 3

Abnormal functioning of this channel, as seen in hypomagnesaemia, causes

Answer 3

reduced PTH release leading to hypocalcemia

Question 4

Slightly reduced magnesium acts similarly to calcium at the CaSR, triggering PTH release from the parathyroid glands.

Answer 4

This results in mild hypercalcemia rather than hypocalcemia.

Question 5

Loop diuretics ……………….. (not activate) the Na-K-2Cl transporter in the thick ascending limb of the loop of Henle. This inhibition can lead to …………………………….

Answer 5

inhibit
hypocalcemia and hypomagnesemia

Question 6

How is classified albuterol

Answer 6

beta-2 agonist

Question 7

Large amounts of inhaled albuterol can cause

Answer 7

Hypokalemia

Question 8

Drugs that cause excessive …………. or ……………. can result in hypokalemia. In addition, any state associated with …………… levels can cause hypokalemia due to increased renal potassium secretion

Answer 8

Diuresis , diarrhea
high aldosterone

Question 9

This woman is experiencing perioral and acral (i.e. hand, foot, ear, nose) paresthesias, along with tetany (muscle twitching). These are common clinical manifestations of hypocalcemia.

Answer 9

hypocalcemi

Question 10

Hypocalcemia has a variety of etiologies including .

Answer 10

hypoparathyroidism, renal failure, and certain medications.

Question 11

Patients that undergo large blood transfusions are at risk

Answer 11

citrate-induced hypocalcemia.

Question 12

.Magnesium normally………………. the ROMK (RenalOuterMedullaryPotassium) potassium channel in the renal collecting duct.

Answer 12

inhibits

Question 13

Low levels of magnesium will remove the inhibition of these channels and therefore cause ……………………… of potassium into the urine.

Answer 13

Excess secretion

Question 14

Malnutrition is part of the underlying cause of ………………………. in alcoholics

Answer 14

hypomagnesaemia

Question 15

Proximal tubular cells in the kidney contain 1a-hydroxylase, an enzyme responsible for producing the active form of ………… Without active vitamin D, there will be poor absorption of ………… from the gastrointestinal tract.

Answer 15

vitamin D
calcium

Question 16

In addition, poor renal function leads to inadequate excretion of phosphate. The end result is ……………………. As a result of low calcium, parathyroid hormone (PTH) levels will rise, but cannot restore calcium-phosphate homeostasis because of poor renal function.

Answer 16

hyperphosphatemic hypocalcemia

Question 17

Incidental hypercalcemia in a middle-aged female is most commonly caused by………………………………… . Phosphate levels may be low but often in primary hyperparathyroidism the serum phosphate is at the low end of the normal range as seen in this case.

Primary hyperparathyroidism is most commonly caused by a singular parathyroid adenoma (80%). Hyperplasia of all glands (15-20%) and carcinoma (<1%) are less likely causes. Patients that are good surgical candidates typically undergo removal of the hyperfunctioning gland.

Answer 17

hyperparathyroidism

Question 18

Primary hyperparathyroidism is the most common cause of “outpatient” hypercalcemia, meaning this diagnosis is most likely in ………………………………………………….

Answer 18

healthy, younger (i.e. not elderly) patients seen in an outpatient setting

Question 19

Primary hyperparathyroidism is most commonly caused by a singular

Answer 19

parathyroid adenoma (80%). Hyperplasia of all glands (15-20%) and carcinoma (<1%) are less likely causes.

Question 20

What CaSR is responsible ?

Answer 20

The CaSR is responsible for detecting low levels of calcium and triggering the release of PTH in response