acid/base disorders, thyroid function, PPP & plasma proteins

Question 1

A patient on levothyroxine presents with nervousness, tremors, and rapid heartbeat, likely from overdose. What laboratory results are most consistent with this?

Answer 1

Decreased TSH with elevated T4 and T3, indicating iatrogenic hyperthyroidism due to excessive thyroid hormone.

Question 2

What is the role of TSH in thyroid hormone regulation?

Answer 2

TSH stimulates the thyroid gland to produce and release T4 and T3; high TSH indicates low thyroid hormone levels and vice versa.

Question 3

What are common symptoms of hyperthyroidism?

Answer 3

Nervousness, tremors, rapid heartbeat (tachycardia), heat intolerance, weight loss, and irritability.

Question 4

How does levothyroxine therapy affect TSH levels?

Answer 4

Adequate levothyroxine suppresses TSH via negative feedback; excessive doses cause low TSH and symptoms of hyperthyroidism.

Question 5

A 58 year-old man is hospitalised due to liver failure. Clinicians suspect advanced hepatocellular carcinoma. If this was the case, what would be the most likely observation following the separation of his serum proteins by electrophoresis?

Answer 5

An increase in alpha-fetoprotein (AFP), a fetal protein elevated in hepatocellular carcinoma.

Question 6

What is alpha-fetoprotein (AFP), and why is it clinically important?

Answer 6

AFP is a fetal serum protein that is elevated in hepatocellular carcinoma and some germ cell tumors, serving as a tumor marker.

Question 7

What changes in immunoglobulin levels might be seen in chronic liver disease?

Answer 7

Immunoglobulin G (IgG) levels may increase due to chronic inflammation or immune activation.

Question 8

In diabetic ketoacidosis, which receptors are activated to cause hyperventilation?

Answer 8

Peripheral chemoreceptors detect low blood pH and stimulate increased ventilation to compensate for metabolic acidosis.

Question 9

What is Kussmaul breathing, and when does it occur?

Answer 9

Kussmaul breathing is deep, labored breathing seen in metabolic acidosis, such as diabetic ketoacidosis, to help reduce CO₂ and raise blood pH.

Question 10

How do central chemoreceptors respond to changes in blood gases?

Answer 10

Central chemoreceptors respond primarily to increases in CO₂ (which lowers pH in cerebrospinal fluid) and stimulate ventilation.

Question 11

What is the primary function of baroreceptors?

Answer 11

Baroreceptors detect changes in blood pressure and help regulate cardiovascular responses.

Question 12

What is the electron donor for cytochrome P450 enzymes during detoxification reactions?

Answer 12

Cytochrome P450 enzymes accept electrons from NADPH via cytochrome P450 reductase to carry out oxidation reactions.

Question 13

Where are cytochrome P450 enzymes primarily located within the cell?

Answer 13

They are primarily located in the smooth endoplasmic reticulum (microsomal fraction), not mitochondria.

Question 14

What is the main function of cytochrome P450 enzymes?

Answer 14

They catalyze oxidation reactions involved in the metabolism of drugs, toxins, and endogenous compounds for detoxification.

Question 15

How does an underactive thyroid gland affect basal metabolic rate (BMR)?

Answer 15

An underactive thyroid gland lowers the basal metabolic rate (BMR), often causing symptoms like feeling cold, fatigue, and weight gain.

Question 16

What is the principal pharmacological action of ethanol?

Answer 16

Ethanol acts primarily as a central nervous system depressant, enhancing inhibitory neurotransmission and causing sedation.

Question 17

In glucose-6-phosphate dehydrogenase deficiency, what decreases and leads to hemolytic anemia?

Answer 17

Reduced glutathione levels decrease, impairing red blood cells’ ability to protect against oxidative damage and causing hemolysis.

Question 18

What is the primary role of glucose-6-phosphate dehydrogenase in red blood cells?

Answer 18

It generates NADPH via the pentose phosphate pathway to maintain reduced glutathione levels.

Question 19

What is the term for abnormal protrusion of the eyeballs, commonly seen in Graves’ disease?

Answer 19

Exophthalmus (or exophthalmos).

Question 20

What is a key renal compensatory mechanism in respiratory acidosis?

Answer 20

The kidneys retain sodium (Na⁺) and water, and excrete hydrogen ions (H⁺) to help restore acid-base balance.

Question 21

How do the kidneys compensate for respiratory acidosis?

Answer 21

By increasing H⁺ excretion and bicarbonate (HCO₃⁻) reabsorption to buffer excess acid.

Question 22

What is the term for enlargement of the thyroid gland?

Answer 22

Goitre.

Question 23

What nutrient deficiency is a common cause of goitre worldwide

Answer 23

iodine deficiency

Question 24

Which protein is present in the β globin fraction during serum protein electrophoresis?

Answer 24

immunoglobulin (especially IgA and some IgM).

Question 25

A 19 year old female presented with persistent vomiting and stomach cramps. She was diagnosed with food poisoning. Her lab test profile showed plasma pH of 7.51, PaCO2 of 49 mmHg, HCO3- of 29 mmol/l and a base excess of 5. Her acid-base status is most likely:

Answer 25

Metabolic alkalosis with respiratory compensation.

Question 26

What is the primary cause of metabolic alkalosis in patients with persistent vomiting?

Answer 26

Loss of gastric acid (HCl) leading to increased bicarbonate concentration.

Question 27

How does the respiratory system compensate for metabolic alkalosis?

Answer 27

By hypoventilating to retain CO₂, which lowers blood pH toward normal.

Question 28

Why does glucose-6-phosphate dehydrogenase deficiency primarily cause damage to red blood cells?

Answer 28

Because red blood cells rely on the pentose phosphate pathway for NADPH production, while other cells have alternative pathways to generate NADPH.

Question 29

Which important protein is NOT synthesized in the liver?

Answer 29

Immunoglobulins are not synthesized in the liver; they are produced by plasma cells.

Question 30

Iodine deficiency used to be a common cause of thyroid enlargement in some parts of the world. Which abnormality in chronically iodine-deficient patients is most directly related to the enlargement of the thyroid gland?

Answer 30

Elevated TSH level

Question 31

what does hyperthyroidism cause in children

Answer 31

Congenital Iodine Deficiency Syndrome

Question 32

A patient has a plasma pH of 7.33, HCO3⁻ of 26 mmol/L, and PaCO2 of 48 mmHg. What is the most likely acid-base disorder?

Answer 32

Respiratory acidosis.

Question 33

what is the antidotal therapy for acetaminophen (paracetamol) overdose?

Answer 33

N-acetylcysteine.

Question 34

Which serum protein appears during an acute phase response and is normally absent or very low?

Answer 34

C-reactive protein

Question 35

NADPH generated from the pentose phosphate pathway is NOT required for which cellular process?

Answer 35

production of ATP