Crushing Endocrine Questions: Your FNP Board Prep Guide to Diabetes, Thyroid, and Adrenal Disorders

Endocrinology · 7 min read · July 4, 2026

Crushing Endocrine Questions: Your FNP Board Prep Guide to Diabetes, Thyroid, and Adrenal Disorders

Hey future FNPs! Are you ready to tackle endocrinology? This system can seem daunting, with its intricate hormonal pathways and complex feedback loops. But don't worry, you've got this! When it comes to your FNP board exams (AANP and ANCC), the focus is on understanding the most common endocrine disorders, their diagnostic criteria, and initial management. We're going to break down the essentials for diabetes mellitus, thyroid disorders, and adrenal gland conditions so you can approach those board questions with confidence.

Decoding Diabetes Mellitus: Type 1, Type 2, and Gestational

Diabetes is a cornerstone of primary care and a high-yield topic for your boards. You need to be crystal clear on the differences, diagnostic criteria, and initial management strategies.

Type 1 Diabetes Mellitus (T1DM)

Pathophysiology: Autoimmune destruction of pancreatic beta cells, leading to absolute insulin deficiency. It often presents in childhood or young adulthood but can occur at any age.
Clinical Presentation: Classic triad of polydipsia (increased thirst), polyuria (increased urination), and polyphagia (increased hunger), often with unexplained weight loss. Patients may present in diabetic ketoacidosis (DKA).
Diagnosis: Fasting plasma glucose (FPG) ≥126 mg/dL, 2-hour plasma glucose (PG) ≥200 mg/dL during an oral glucose tolerance test (OGTT), or A1C ≥6.5%. Random PG ≥200 mg/dL with classic symptoms also diagnostic.
Management: Lifelong insulin therapy is essential. Education on insulin administration, glucose monitoring, nutrition, and exercise.

Type 2 Diabetes Mellitus (T2DM)

Pathophysiology: Progressive insulin secretory defect with insulin resistance. Often associated with obesity, sedentary lifestyle, and genetic predisposition.
Clinical Presentation: Can be asymptomatic for years. Symptoms are similar to T1DM but often less acute. May present with recurrent infections, blurred vision, or paresthesias.
Diagnosis: Same criteria as T1DM (FPG ≥126 mg/dL, 2-hour PG ≥200 mg/dL, A1C ≥6.5%, or random PG ≥200 mg/dL with symptoms).
Management: Lifestyle modifications (diet, exercise) are foundational. Initial pharmacotherapy often starts with metformin, unless contraindicated. Other oral agents or injectables (GLP-1 receptor agonists, SGLT2 inhibitors) may be added. Insulin may be required as the disease progresses.

Gestational Diabetes Mellitus (GDM)

Pathophysiology: Glucose intolerance that develops or is first recognized during pregnancy. Hormonal changes during pregnancy lead to increased insulin resistance.
Screening: Typically performed between 24 and 28 weeks gestation.
- One-step approach (ADA recommended): 75-gram OGTT. Diagnosis if any of the following are met or exceeded: FPG ≥92 mg/dL, 1-hour PG ≥180 mg/dL, 2-hour PG ≥153 mg/dL.
- Two-step approach: 1-hour 50-gram glucose challenge test (GCT). If plasma glucose is ≥130-140 mg/dL, proceed to a 3-hour 100-gram OGTT. Diagnosis if two or more values are met or exceeded: FPG ≥95 mg/dL, 1-hour PG ≥180 mg/dL, 2-hour PG ≥155 mg/dL, 3-hour PG ≥140 mg/dL.
Management: Nutritional therapy and exercise are first-line. Insulin is the preferred pharmacologic agent if lifestyle changes are insufficient. Oral agents like metformin or glyburide may be used in select cases.

Clinical Pearl: Remember the diagnostic numbers for diabetes! FPG ≥126, 2-hour OGTT ≥200, A1C ≥6.5. A random glucose ≥200 with symptoms is also diagnostic. For GDM, know the screening timelines and diagnostic thresholds for both the one-step and two-step approaches.

Navigating Thyroid Disorders: Hypo- and Hyperthyroidism

Thyroid conditions are extremely common in primary care. Your boards will test your ability to differentiate between hypothyroidism and hyperthyroidism, understand their causes, and know the initial steps in management.

Hypothyroidism

Pathophysiology: Underproduction of thyroid hormones (T3 and T4) by the thyroid gland. The most common cause is Hashimoto's thyroiditis (an autoimmune disease).
Clinical Presentation: Slowed metabolism. Symptoms include fatigue, weight gain, cold intolerance, constipation, dry skin, hair loss, bradycardia, and menstrual irregularities. In severe cases, myxedema coma.
Diagnosis: Elevated TSH (thyroid-stimulating hormone) and low free T4 (thyroxine). Subclinical hypothyroidism has elevated TSH with normal free T4.
Management: Lifelong thyroid hormone replacement, typically with levothyroxine. Dosing is individualized and monitored by TSH levels.

Hyperthyroidism

Pathophysiology: Overproduction of thyroid hormones. The most common cause is Graves' disease (an autoimmune disorder).
Clinical Presentation: Accelerated metabolism. Symptoms include weight loss despite increased appetite, heat intolerance, palpitations, anxiety, tremor, diarrhea, and exophthalmos (in Graves' disease). In severe cases, thyroid storm.
Diagnosis: Suppressed TSH and elevated free T4 (and sometimes free T3). In Graves' disease, you may see positive thyroid-stimulating immunoglobulins (TSI).
Management: Antithyroid medications (e.g., methimazole, propylthiouracil), radioactive iodine ablation, or surgery. Beta-blockers can help manage symptoms like palpitations and tremor.

Clinical Pearl: Think of TSH as the 'boss' and T4 as the 'worker'. In hypothyroidism, the boss (TSH) is yelling loudly (high) to a lazy worker (low T4). In hyperthyroidism, the boss (TSH) is quiet (low) because the worker (T4) is overactive (high).

Adrenal Gland Conditions: Cushing's, Addison's, and Pheochromocytoma

The adrenal glands, though small, play a huge role in stress response, metabolism, and blood pressure. Boards often feature questions on their dysfunction.

Cushing's Syndrome

Pathophysiology: Prolonged exposure to excessively high levels of cortisol.
- Exogenous: Most common, due to long-term corticosteroid use.
- Endogenous: Adrenal tumor, pituitary adenoma (Cushing's disease), or ectopic ACTH production.
Clinical Presentation: Weight gain (central obesity, moon facies, buffalo hump), thin skin, easy bruising, purple striae, muscle weakness, hypertension, hyperglycemia, osteoporosis, mood changes.
Diagnosis: 24-hour urinary free cortisol, late-night salivary cortisol, or low-dose dexamethasone suppression test. Further testing to determine the cause.
Management: Depends on the cause. Tapering exogenous steroids, surgical removal of tumors, medications to block cortisol production.

Addison's Disease (Primary Adrenal Insufficiency)

Pathophysiology: Adrenal glands fail to produce enough cortisol and often aldosterone. Most commonly autoimmune destruction of the adrenal cortex.
Clinical Presentation: Gradual onset of fatigue, weakness, weight loss, anorexia, nausea/vomiting, abdominal pain, hyperpigmentation (especially in skin creases, scars, and mucous membranes due to high ACTH). Hypotension, hyponatremia, hyperkalemia.
Diagnosis: Morning serum cortisol (low) and elevated ACTH. ACTH stimulation test (Cosyntropin test) is confirmatory: cortisol levels fail to rise after ACTH administration.
Management: Lifelong hormone replacement with hydrocortisone (for cortisol) and often fludrocortisone (for aldosterone). Patients need stress-dose steroids during illness or surgery.

Pheochromocytoma

Pathophysiology: Rare tumor of the adrenal medulla that produces excessive catecholamines (epinephrine, norepinephrine).
Clinical Presentation: Classic triad of paroxysmal hypertension, palpitations, and headaches, often accompanied by sweating, anxiety, and tremor. Can be sustained or episodic.
Diagnosis: 24-hour urinary fractionated metanephrines and catecholamines, or plasma free metanephrines. Imaging (CT/MRI) of the abdomen to locate the tumor.
Management: Surgical removal of the tumor after adequate alpha-blockade (e.g., phenoxybenzamine) to control blood pressure, followed by beta-blockade if needed. This sequence is critical to prevent a hypertensive crisis during surgery.

Clinical Pearl: For Addison's, think "ADD" – ACTH is Deficient, Dark skin (hyperpigmentation due to high ACTH). For Cushing's, think "CUSH" – Cortisol Up, Striae, Hypertension.

Key Takeaways for Your Board Exam

Endocrinology is all about understanding the hormones and their effects. For your boards, focus on:

Diagnostic Criteria: Know the specific lab values that confirm a diagnosis.
Cardinal Symptoms: Identify the classic presentations that distinguish one condition from another.
First-Line Management: Understand the initial treatment strategies, especially for common conditions like diabetes and thyroid disorders.

Board Tip: When presented with a case study, always identify the primary hormone imbalance first. Is it too much or too little of a specific hormone? Then, relate that to the clinical picture.

Don't let the complexity of endocrinology intimidate you. Break it down, focus on the high-yield information, and trust your clinical reasoning. You've been building this knowledge throughout your program, and now it's time to shine!

Ready to put your endocrine knowledge to the test? Visit The FNP Review for thousands of practice questions designed to mimic the board exam experience and solidify your understanding. You're closer than you think to becoming a certified FNP!