Endocrine & Metabolic

The hypothalamus normally maintains core temperature at 37°C, but this set-point is altered in fever and may be lost in hypothalamic disease.

Answer: A
Explanation: Diabetic ketoacidosis (DKA) is most common in type 1 diabetes due to the absolute insulin deficiency. Davidson explains that without insulin, the body shifts to fat metabolism, producing ketones and leading to metabolic acidosis. Harrison adds that DKA can occur in type 2 diabetes under extreme stress, but it is far less common.

Ref: Davidson 23rd; P-1047

Explanation: Night blindness occurs due to Vitamin A deficiency

Drugs causing hypothyroidism
Carbimazole, methimazole, popylthiouracil
Amiodarone
Lithium

It is the innermost part of the adrenal gland, consisting of chromaffin cells that secrete catecholamines, including epinephrine (adrenaline), norepinephrine (noradrenaline), and a small amount of dopamine, in response to stimulation by sympathetic preganglionic neurons.

Chronic kidney disease (CKD) is the most common cause of secondary hyperparathyroidism. Davidson explains that in CKD, impaired phosphate excretion and decreased production of active vitamin D (calcitriol) lead to hypocalcemia, which stimulates parathyroid hormone (PTH) release. Harrison adds that secondary hyperparathyroidism is an adaptive response to maintain normal calcium levels but can lead to renal osteodystrophy if left untreated.

Reference: Davidson 23rd; P-668

Explanation: Niacin Deficiency – pellagra, Thiamin Deficiency – beri-beri

Reference: Davidson 23rd , Page : 718
Explanation : keshan’s disease ( cardiomyopathy in children ) occurs due to selenium deficiency .

• Patient feeling feverish with excessive sweating—Thyrotoxicosis.

Reference: Davidson 23rd, Box-18.11

Reference: Davidson 23rd; P-665

Stem Breakdown:

Heat intolerance, palpitations, weight loss, and diarrhoea: These symptoms are classic for hyperthyroidism, indicating increased metabolism.
Diffusely enlarged thyroid: A diffusely enlarged thyroid without nodularity is characteristic of Graves’ disease.
Low TSH and elevated free T4: These lab findings confirm hyperthyroidism, with low TSH due to feedback inhibition and high free T4 indicating excessive thyroid hormone production.
Option Analysis:

A) Graves’ disease: This is the correct diagnosis. Davidson and Harrison describe Graves’ disease as the most common cause of hyperthyroidism, characterised by a diffusely enlarged thyroid gland, low TSH, and elevated free T4. Graves' disease is caused by autoantibodies that stimulate the TSH receptor, leading to increased thyroid hormone production.
B) Subacute thyroiditis: Subacute thyroiditis can cause transient hyperthyroidism due to the release of preformed thyroid hormone, but it is usually associated with neck pain and tenderness, not a diffusely enlarged thyroid.
C) Toxic multinodular goitre: Toxic multinodular goitre causes hyperthyroidism due to the presence of multiple autonomous thyroid nodules. The thyroid gland is typically irregular and nodular, not diffusely enlarged.
D) Hashimoto’s thyroiditis: Hashimoto's thyroiditis is a common cause of hypothyroidism, not hyperthyroidism. It causes a firm, enlarged thyroid and is associated with high TSH and low T4 levels.

Reference: Davidson 23rd; P-748

Explanation: Obesity is regarded as a pandemic, with potentially disastrous consequences for human health.

Reference: Davidson 23rd; P-638

Scurvy
Vitamin C deciency affects the normal synthesis of collagen and results in a bleeding disorder characterised by perifollicular and petechial haemorrhage, bruising and subperiosteal bleeding. The key to diagnosis is the dietary history

Reference: Davidson 23rd; P-637

Hyperkalaemia is a common finding in adrenal insufficiency due to decreased aldosterone secretion. Davidson explains that oestrogen normally promotes sodium reabsorption and potassium excretion in the kidneys. In Addison’s disease, low aldosterone levels lead to sodium loss and potassium retention. Harrison adds that adrenal insufficiency also leads to hyponatremia and volume depletion due to salt wasting.

(Ref : Davidson 23rd ,p – 692 )

Reference: Davidson 23rd; P-772
সলভ ক্লাসের জন্য আলোচনা পোস্ট দেখুন - [আলোচনা পোস্টের লিঙ্ক]

Reference: Davidson 23rd; P-749

Osteoporosis is a well-known side effect of long-term corticosteroid therapy. Davidson explains that corticosteroids reduce bone formation and increase bone resorption, leading to decreased bone density and an increased risk of fractures. Harrison adds that patients on long-term corticosteroids should be monitored for bone loss and may require prophylactic treatment with calcium, vitamin D, and bisphosphonates to reduce the risk of osteoporosis.

Explanation: Turner’s syndrome (45,X) is an example of Numerical chromosomal abnormalities

( Ref : Davidson 23rd ,p - 712 , box : 19.32 )

Explanation: Vitamins are organic substances with key roles in certain metabolic pathways, and are categorised into those that are fat-soluble (vitamins A, D, E and K) and those that are water-soluble (vitamins of the B complex group and vitamin C).

Reference: Davidson 23rd; P-634

Reference: Davidson 23rd; P-746

Reference: Davidson 23rd, Page: 644 , Box : 18.14

Explanation: Features of an acute adrenal crisis include circulatory shock with severe hypotension, hyponatraemia, hyperkalaemia and, in some instances, hypoglycaemia and hypercalcaemia.

Reference: Davidson 23rd; P-644

Reference: Davidson 23rd; P-746

Stem Breakdown:

Polyuria, polydipsia, and nocturia: These are classic symptoms of diabetes mellitus, indicating hyperglycemia leading to osmotic diuresis.
Fasting blood glucose of 170 mg/dL and haemoglobin A1c of 8.2%: These results confirm persistent hyperglycemia and meet the diagnostic criteria for diabetes mellitus (fasting blood glucose ≥126 mg/dL, A1c ≥6.5%).
Option Analysis:

A) Type 1 diabetes mellitus: Type 1 diabetes usually presents in younger individuals with an acute onset of symptoms (polyuria, weight loss) and often requires insulin from the onset. This patient’s presentation, age, and gradual development of symptoms are more consistent with type 2 diabetes.
B) Type 2 diabetes mellitus: This is the correct diagnosis. Davidson and Harrison explain that type 2 diabetes is the most common form of diabetes, typically occurring in middle-aged or older adults, often with a gradual onset. It is characterised by insulin resistance and relative insulin deficiency, leading to elevated fasting blood glucose and A1c levels.
C) Diabetes insipidus: Diabetes insipidus is characterised by polyuria and polydipsia, but it results from a deficiency of antidiuretic hormone (ADH) or renal insensitivity to ADH. Blood glucose levels would be normal, not elevated.
D) Hyperosmolar hyperglycaemic state (HHS): HHS is a life-threatening complication of type 2 diabetes, characterised by extreme hyperglycemia (>600 mg/dL), dehydration, and altered mental status. The patient in this case has elevated glucose but is not in HHS.

(Ref : Davidson 23rd ,p-703 )

Less common sign in hypothyroidism
Goitre with bruit
Atrial fibrillation
Systolic hypertension/increased
pulse pressure
Cardiac failure
Hyper-reexia
Ill-sustained clonus
Proximal myopathy
Bulbar myopathy

Less common sign in hyperthyroidism
Hoarse voice
Facial features:
Purplish lips
Malar flush
Periorbital oedema
Loss of lateral eyebrows
Anaemia
Carotenaemia
Erythema ab igne
Bradycardia hypertension
Delayed relaxation of reexes
Dermal myxoedema

The low-dose dexamethasone suppression test is the best screening test for Cushing’s syndrome. Davidson explains that in Cushing’s syndrome, cortisol secretion fails to be suppressed by dexamethasone, indicating autonomous cortisol production. Harrison adds that a 24-hour urine cortisol measurement can also be used to confirm the diagnosis, but the dexamethasone suppression test is more sensitive for detecting mild hypercortisolism.

( Ref : Davidson 23rd ,p – 700 )

Reference: Davidson 23rd; P-669