Endocrine: the axes and their extremes

Read every hormone item as too much or too little of one thing. Name the axis, then name the direction, and the disease name becomes optional.

Thyroid low

• Metabolism slows. The patient is cold, constipated, bradycardic, gaining weight, hoarse, and mentally sluggish, with dry skin and thinning hair.
• The extreme is myxedema coma: hypothermia, hypoventilation, hypotension, and depressed consciousness, precipitated by cold, infection, or stopping therapy.

Thyroid high

• Metabolism accelerates. The patient is hot, tachycardic, losing weight while eating well, tremulous, anxious, and having frequent stools.
• The extreme is thyroid storm: high fever, severe tachycardia, and agitation, often triggered by infection or by thyroid surgery.

Adrenal low

• Too little cortisol and aldosterone gives hypotension, hyponatremia, hyperkalemia, hypoglycemia, salt craving, fatigue, and darkening of skin creases.
• Adrenal crisis is a shock state. Abruptly stopping long-term corticosteroids is the classic precipitant.

Adrenal high

• Too much cortisol gives central obesity with thin extremities, fragile bruising skin, hyperglycemia, hypertension, muscle wasting, and blunted immunity.
• Infection in these patients presents without the usual fever and inflammation, so a small change is a large signal.

Glucose low

• The brain runs out of fuel first: shakiness, diaphoresis, pallor, irritability, confusion, then loss of consciousness.
• Hypoglycemia is always treated before hyperglycemia is investigated. A patient who cannot swallow safely is given nothing by mouth.

Glucose high

• Two faces. The ketotic one develops over hours with deep rapid breathing, fruity breath, and acidosis. The hyperosmolar one develops over days with profound dehydration, very high glucose, altered mentation, and little ketosis.
• Both are fluid problems before they are insulin problems.

Water balance

• Retaining water dilutes serum sodium and concentrates the urine, giving weight gain, headache, and confusion.
• Losing water concentrates serum sodium, giving enormous volumes of dilute urine and relentless thirst.
• The exam separates the two by urine appearance and the direction of serum sodium, never by hormone name alone.

Margin notetoo much burns, too little slows.

Watch outany patient on long-term corticosteroids who stops them suddenly can crash into adrenal crisis.

TakeawayEvery endocrine item is a direction question, so name the axis and the direction before reaching for the disease name.

→ BOOK 10 · P7 for the endocrine crises · → BOOK 05 · P6 for insulin · → BOOK 07 · P10 for the values