# Clinical Cases: Peptides and Hormones

## Case 1: Growth Hormone Deficiency in Adult

### Patient Presentation
**Demographics:** 42-year-old male software developer

**Chief Complaint:** "I feel like I'm aging faster than I should. I've lost muscle, gained belly fat, and my energy is terrible."

**History of Present Illness:**
The patient presents with a 3-year history of progressive body composition changes, fatigue, and diminished quality of life. He reports a 12 kg increase in truncal adiposity despite maintaining his exercise routine, along with noticeable loss of muscle mass in his arms and legs. He describes his energy as "running on empty," with an inability to sustain the physical and cognitive output he could 5 years ago.

He reports decreased exercise capacity, noting that his gym performance has declined substantially. Recovery from workouts takes 2-3 days compared to his previous 24-hour recovery time. He also describes dry, thinning skin, impaired sleep quality with reduced deep sleep phases, increased anxiety, social withdrawal, and diminished emotional resilience.

His symptoms began gradually after a traumatic brain injury sustained in a mountain biking accident 4 years ago, which involved a brief loss of consciousness (< 5 minutes) and a frontal contusion identified on CT at the time. He was managed conservatively and made a good neurological recovery but has noted progressive endocrine symptoms since.

**Past Medical History:**
- Traumatic brain injury (4 years ago, mild-moderate)
- Concussion history (2 prior sports-related concussions in college)
- No prior endocrine diagnoses

**Medications:**
- None currently
- Previously tried DHEA 50 mg daily (self-directed, minimal benefit)

**Social History:**
- Non-smoker, minimal alcohol
- Regular gym-goer (4x/week resistance training)
- Single, lives alone
- High-stress job but manages well
- 7 hours sleep per night but poor quality

**Family History:**
- Father: Type 2 diabetes
- Mother: Osteoporosis
- No family history of pituitary disease

### Physical Examination
- **Vital Signs:** BP 118/74 mmHg, HR 72 bpm, RR 14, Temp 36.7°C, SpO2 99% RA, BMI 28.6, Waist circumference 98 cm
- **General:** Appears stated age, increased truncal adiposity with relatively thin extremities
- **HEENT:** Normal visual fields by confrontation, no papilledema
- **Skin:** Thin, dry skin with reduced turgor, fine wrinkles around eyes
- **Cardiovascular:** Regular rate and rhythm, no murmurs
- **Abdomen:** Central adiposity, soft, non-tender
- **Musculoskeletal:** Decreased muscle bulk in deltoids, biceps, and quadriceps relative to expected for activity level
- **Neurological:** Cranial nerves intact, no focal deficits, normal cognition on bedside testing

### Workup and Results

**Laboratory Studies:**
| Test | Result | Reference Range |
|------|--------|-----------------|
| IGF-1 | 88 ng/mL | 101-267 ng/mL (age-adjusted) |
| GH (random) | 0.1 ng/mL | 0.0-8.0 ng/mL |
| GHRH-arginine stimulation test: Peak GH | 4.2 ng/mL | > 11.0 ng/mL (BMI-adjusted cutoff for BMI 25-30) |
| Insulin tolerance test: Peak GH | 3.1 ng/mL | > 5.0 ng/mL |
| Cortisol (AM, 8 AM) | 12.4 mcg/dL | 6.2-19.4 mcg/dL |
| Cortisol peak (ITT) | 22.1 mcg/dL | > 18 mcg/dL |
| TSH | 2.1 mIU/L | 0.4-4.0 mIU/L |
| Free T4 | 1.2 ng/dL | 0.8-1.8 ng/dL |
| Total testosterone | 480 ng/dL | 250-836 ng/dL |
| Free testosterone | 9.8 ng/dL | 5.0-21.0 ng/dL |
| LH | 4.2 IU/L | 1.5-9.3 IU/L |
| FSH | 5.1 IU/L | 1.4-18.1 IU/L |
| Prolactin | 9.8 ng/mL | 2.1-17.7 ng/mL |
| Fasting glucose | 102 mg/dL | 70-100 mg/dL |
| Fasting insulin | 16.4 mU/L | 2.6-11.1 mU/L |
| HbA1c | 5.8% | < 5.7% |
| Lipid panel | TC 224, LDL 148, HDL 38, TG 190 | TC <200, LDL <100, HDL >40, TG <150 |
| DEXA body composition | Total fat 32%, lean mass reduced | Age-matched norms |
| DEXA bone density | T-score lumbar spine -1.6, hip -1.2 | > -1.0 normal |

**Imaging/Additional Studies:**
- MRI pituitary with contrast: Small pituitary gland (height 3.2 mm, lower limit of normal), partially empty sella, no adenoma or mass lesion, stalk midline
- DEXA body composition: Increased truncal fat, reduced appendicular lean mass index
- Carotid intima-media thickness: 0.82 mm (above 75th percentile for age, indicating subclinical atherosclerosis)
- Quality of Life Assessment (QoL-AGHDA): Score 18/25 (significant impairment)

### Clinical Image

![GH-IGF-1 axis and effects of adult GH deficiency](case_01_image.jpg)

*Diagram illustrating the somatotropic (GH-IGF-1) axis showing hypothalamic GHRH and somatostatin regulation of pituitary GH release, hepatic IGF-1 production, and the metabolic consequences of adult GH deficiency on body composition, cardiovascular health, bone density, and quality of life. Source: Educational illustration.*

### Diagnosis
**Adult-Onset Growth Hormone Deficiency (AO-GHD) Secondary to Traumatic Brain Injury, with Metabolic Syndrome, Osteopenia, and Subclinical Atherosclerosis**

**Key Diagnostic Criteria:**
- Low IGF-1 (88 ng/mL) below age-adjusted reference range
- Failed two dynamic stimulation tests: GHRH-arginine peak GH 4.2 ng/mL (cutoff > 11 for BMI 25-30) and ITT peak GH 3.1 ng/mL (cutoff > 5)
- Identified etiology: traumatic brain injury (TBI is recognized cause of hypopituitarism, GH axis most commonly affected)
- Partially empty sella on MRI consistent with pituitary atrophy
- Clinical phenotype of AO-GHD: increased truncal fat, decreased lean mass, dyslipidemia, osteopenia, impaired quality of life
- Other pituitary axes intact (cortisol response adequate on ITT, normal thyroid and gonadal function)

### Treatment Plan
1. **Growth hormone replacement therapy:**
   - Recombinant human GH (somatropin) starting dose 0.2 mg/day subcutaneous injection at bedtime (lower starting dose for males; females typically require higher doses)
   - Titrate dose by 0.1-0.2 mg every 4-6 weeks based on IGF-1 levels (target mid-to-upper normal range for age) and clinical response
   - Expected maintenance dose 0.4-0.8 mg/day
   - Alternative: Somapacitan (long-acting GH analog) 1.5 mg/week SC for improved adherence if cost permits
2. **Monitoring protocol:**
   - IGF-1 levels at 1, 3, 6, and 12 months, then every 6 months
   - Fasting glucose, HbA1c, and insulin at 3 and 6 months (GH can worsen insulin resistance initially)
   - Lipid panel at 6 months (expect improvement in LDL and total cholesterol)
   - Free T4 at 3 and 6 months (GH can unmask central hypothyroidism by increasing T4-to-T3 conversion)
   - DEXA body composition and bone density at 12 months
   - Quality of life assessment (QoL-AGHDA) at 6 and 12 months
3. **Metabolic optimization:**
   - Structured resistance training program (maintain current 4x/week, progressive overload)
   - Dietary modification: increase protein to 1.6 g/kg/day, reduce refined carbohydrates, Mediterranean pattern
   - Monitor glucose closely given pre-diabetes and GH-mediated insulin antagonism
4. **Cardiovascular risk management:**
   - Address dyslipidemia (may improve with GH replacement, reassess statin need at 6 months)
   - Repeat carotid IMT at 12 months
5. **Side effect counseling:** Arthralgia, peripheral edema, and carpal tunnel syndrome are common dose-dependent side effects; managed with dose reduction. Review symptoms at each visit.
6. **Long-term screening:** Annual pituitary hormone panel to monitor for evolution of additional axis deficits post-TBI

### Key Learning Points
- Traumatic brain injury (even mild-moderate) is an underrecognized cause of hypopituitarism, with the GH axis being the most vulnerable; prevalence of GHD post-TBI ranges from 10-30% and can manifest months to years after injury
- Diagnosis of adult GHD requires a low IGF-1 combined with failure of at least one dynamic stimulation test (ITT remains gold standard; GHRH-arginine is acceptable alternative), with BMI-adjusted cutoffs for the GHRH-arginine test
- Adult GHD is associated with adverse metabolic profile (visceral obesity, dyslipidemia, insulin resistance), increased cardiovascular risk, reduced bone density, and significantly impaired quality of life that responds to GH replacement
- GH replacement can initially worsen glucose tolerance through insulin antagonism; careful monitoring is essential in patients with pre-existing insulin resistance or pre-diabetes
- GH treatment may unmask central hypothyroidism by enhancing peripheral conversion of T4 to T3, necessitating thyroid function monitoring during therapy initiation

---

## Case 2: Hypothalamic-Pituitary-Adrenal Axis Dysfunction

### Patient Presentation
**Demographics:** 36-year-old female physician (emergency medicine resident)

**Chief Complaint:** "I can't function anymore. I crash in the afternoons, I can't handle stress like I used to, and I get dizzy every time I stand up."

**History of Present Illness:**
The patient presents with a 2-year history of progressive fatigue, stress intolerance, and orthostatic symptoms in the context of chronic high-intensity work demands. She works 60-70 hour weeks including overnight shifts in a busy emergency department. She reports profound fatigue particularly between 2-4 PM and again at 8-9 PM, with paradoxical wakefulness at 11 PM-midnight making sleep initiation difficult.

She describes a markedly diminished ability to cope with stress that she previously managed well. Minor stressors now provoke disproportionate anxiety, irritability, or tearfulness. She reports salt cravings, frequent lightheadedness when standing from a seated position, and has nearly fainted twice in the past 3 months. She notes frequent non-specific infections (3 upper respiratory infections and 2 episodes of oral herpes in 6 months) and prolonged recovery times.

She has also developed diffuse myalgias, brain fog, and reactive hypoglycemia episodes (shakiness, confusion, and sweating 2-3 hours after meals, relieved by eating). She self-treats with frequent caffeine (6+ cups of coffee daily) and notes that her symptoms transiently improve with caffeine and worsen significantly during days off when she attempts to rest.

**Past Medical History:**
- No formal diagnoses
- History of high academic achievement and chronic overwork since medical school
- Recurrent viral infections (increased frequency over 2 years)
- Amenorrhea for 8 months (previously regular cycles)

**Medications:**
- Oral contraceptive pill (combined ethinylestradiol/levonorgestrel) - recently stopped
- Caffeine (estimated 600+ mg daily)
- Melatonin 5 mg at bedtime intermittently

**Social History:**
- Non-smoker, rare alcohol
- No regular exercise (previously ran half-marathons)
- Overnight shift work (rotating schedule)
- Chronically sleep-deprived (averaging 4-5 hours per 24 hours)
- Living alone, limited social connections due to schedule
- Diet: erratic meal timing, high in processed food and caffeine

**Family History:**
- Mother: Hashimoto thyroiditis
- Father: Healthy
- Sister: Addison disease (autoimmune)

### Physical Examination
- **Vital Signs:** BP 98/62 mmHg supine, 84/54 mmHg standing (orthostatic positive), HR 72 supine, 98 standing (orthostatic positive), RR 14, Temp 36.2°C, SpO2 99% RA, BMI 21.4
- **General:** Thin, fatigued-appearing female with dark periorbital circles
- **Skin:** Slight hyperpigmentation of palmar creases and buccal mucosa, dry skin, no striae
- **HEENT:** Mild conjunctival pallor
- **Thyroid:** Normal size, non-tender, no nodules
- **Cardiovascular:** Regular, no murmurs, soft S1
- **Abdomen:** Soft, non-tender, thin habitus
- **Musculoskeletal:** Mild diffuse tenderness, reduced grip strength
- **Neurological:** Normal cranial nerves, mildly delayed relaxation of ankle reflexes
- **Psychiatric:** Flat affect, appears exhausted, speech slow and effortful

### Workup and Results

**Laboratory Studies:**
| Test | Result | Reference Range |
|------|--------|-----------------|
| Cortisol (8 AM, non-shift day) | 4.8 mcg/dL | 6.2-19.4 mcg/dL |
| Cortisol (8 AM repeat) | 5.2 mcg/dL | 6.2-19.4 mcg/dL |
| ACTH (8 AM) | 48 pg/mL | 7-63 pg/mL |
| ACTH stimulation test (250 mcg cosyntropin): 0 min | 5.0 mcg/dL | - |
| ACTH stimulation test: 30 min | 16.2 mcg/dL | > 18 mcg/dL |
| ACTH stimulation test: 60 min | 17.8 mcg/dL | > 18 mcg/dL |
| Low-dose (1 mcg) cosyntropin test: 30 min | 14.4 mcg/dL | > 18 mcg/dL |
| DHEA-S | 42 mcg/dL | 95-530 mcg/dL |
| Salivary cortisol (4-point diurnal): Morning | 0.18 mcg/dL | 0.25-0.60 mcg/dL |
| Salivary cortisol: Noon | 0.14 mcg/dL | 0.10-0.30 mcg/dL |
| Salivary cortisol: Evening | 0.12 mcg/dL | 0.04-0.15 mcg/dL |
| Salivary cortisol: Night | 0.09 mcg/dL | 0.02-0.08 mcg/dL |
| 24-hr urinary free cortisol | 18 mcg/24hr | 20-90 mcg/24hr |
| TSH | 4.8 mIU/L | 0.4-4.0 mIU/L |
| Free T4 | 0.9 ng/dL | 0.8-1.8 ng/dL |
| Free T3 | 2.0 pg/mL | 2.3-4.2 pg/mL |
| Anti-TPO antibodies | 186 IU/mL | < 35 IU/mL |
| Anti-21-hydroxylase antibodies | Negative | Negative |
| CBC | WBC 3.8, Lymphocytes 1.2 | WBC 4.5-11, Lymph 1.0-4.8 |
| Sodium | 134 mEq/L | 136-145 mEq/L |
| Potassium | 4.8 mEq/L | 3.5-5.0 mEq/L |
| Fasting glucose | 68 mg/dL | 70-100 mg/dL |
| Aldosterone | 4.2 ng/dL | 3-16 ng/dL |
| Renin activity | 3.8 ng/mL/hr | 0.5-3.0 ng/mL/hr |
| Ferritin | 8 ng/mL | 12-150 ng/mL |
| Vitamin D | 16 ng/mL | 30-100 ng/mL |
| LH | 1.2 IU/L | 1.9-12.5 IU/L |
| FSH | 1.8 IU/L | 2.5-10.2 IU/L |
| Estradiol | 18 pg/mL | 21-312 pg/mL (follicular) |

### **Imaging/Additional Studies:**
- DUTCH Complete Hormone Test: Flattened cortisol diurnal curve with blunted cortisol awakening response, low cortisol metabolites, reduced cortisone-to-cortisol ratio suggesting 11-beta-HSD1 dysregulation, low DHEA metabolites
- MRI pituitary: Normal size and morphology, no adenoma
- CT adrenals: Normal bilateral adrenal glands, no atrophy or masses
- Thyroid ultrasound: Mild diffuse heterogeneity consistent with early thyroiditis, no nodules

### Clinical Image

![HPA axis dysfunction spectrum](case_02_image.jpg)

*Diagram illustrating the spectrum of HPA axis dysfunction from normal stress response through maladaptive stages: initial hyperactivation with elevated cortisol, progression to blunted diurnal rhythm with preserved total output, and eventual hypothalamic downregulation with low cortisol output. Shows contributing factors including chronic stress, sleep deprivation, circadian disruption, and nutritional deficiency. Source: Educational illustration.*

### Diagnosis
**Hypothalamic-Pituitary-Adrenal Axis Dysfunction with Suboptimal Cortisol Response, Functional Hypothalamic Amenorrhea, Early Hashimoto Thyroiditis, Iron Deficiency, and Vitamin D Deficiency**

**Key Diagnostic Criteria:**
- Low morning serum cortisol on two occasions (4.8 and 5.2 mcg/dL) with suboptimal (but not absent) cosyntropin response
- Flattened salivary cortisol diurnal curve with blunted cortisol awakening response
- Low urinary free cortisol (18 mcg/24hr)
- Severely depressed DHEA-S indicating adrenal reserve depletion
- Normal ACTH (not elevated as in primary Addison), negative anti-21-hydroxylase antibodies
- Normal adrenal imaging excluding structural disease
- Concurrent functional hypothalamic amenorrhea (low LH, FSH, estradiol) from chronic energy deficit and stress
- Early Hashimoto thyroiditis (elevated TPO antibodies, borderline high TSH, low-normal free T3/T4)
- Clear precipitating context: chronic sleep deprivation, circadian disruption, caloric insufficiency, and sustained psychological stress

### Treatment Plan
1. **Foundational interventions (non-negotiable):**
   - **Work schedule modification:** Formal occupational health referral; reduce to 50-hour maximum work weeks, eliminate consecutive overnight shifts, request minimum 48-hour recovery between night shifts; this is the root cause and must be addressed or treatment will fail
   - **Sleep restoration:** Sleep hygiene optimization, target 7-8 hours per 24 hours, blackout curtains, post-night shift sleep protocol, gradual caffeine taper to < 200 mg daily (morning only)
   - **Nutritional rehabilitation:** Regular meal timing every 3-4 hours, adequate caloric intake (minimum 2000 kcal/day), complex carbohydrates with protein at each meal to prevent reactive hypoglycemia, increase salt intake to 6-8 g/day for orthostatic support
2. **Adrenal support protocol:**
   - Hydrocortisone 10 mg on waking + 5 mg at noon during recovery phase (physiologic replacement, not pharmacologic), taper over 8-12 weeks as HPA axis recovers
   - DHEA 25 mg daily morning (given severely depleted DHEA-S)
   - Adaptogenic herbs: Rhodiola rosea 200 mg morning + Ashwagandha 300 mg BID (evidence for HPA axis modulation)
   - Phosphatidylserine 300 mg at bedtime (blunts nocturnal cortisol and supports sleep)
   - Vitamin C 1000 mg daily (adrenal cortex has highest vitamin C concentration of any organ)
3. **Thyroid management:**
   - Start levothyroxine 25 mcg daily given symptomatic subclinical hypothyroidism with positive antibodies, family history, and context (caution: do not start thyroid replacement before ensuring adequate cortisol, as T4 replacement increases cortisol metabolism)
   - Selenium 200 mcg daily (evidence for reducing TPO antibodies in Hashimoto)
   - Recheck TSH, free T4, free T3 at 6 weeks
4. **Nutritional deficiency correction:**
   - Iron bisglycinate 45 mg daily with vitamin C (ferritin goal > 50)
   - Vitamin D3 5000 IU daily with K2
   - Magnesium glycinate 400 mg at bedtime
5. **Amenorrhea management:**
   - Expected to resolve with caloric restoration, stress reduction, and cortisol normalization
   - If persistent at 6 months, consider pulsatile GnRH or low-dose estrogen replacement for bone protection
   - DEXA scan if amenorrhea persists > 12 months total
6. **Follow-up:** Repeat morning cortisol, DHEA-S, and 4-point salivary cortisol at 8 weeks; TSH and free T4 at 6 weeks; ferritin and vitamin D at 8 weeks; menstrual diary; repeat cosyntropin test at 6 months

### Key Learning Points
- HPA axis dysfunction from chronic stress is a real clinical entity characterized by blunted cortisol diurnal rhythm and suboptimal (but not absent) stimulation test responses; it is distinct from Addison disease and requires different management
- The low-dose (1 mcg) cosyntropin test is more sensitive than the standard 250 mcg test for detecting subtle adrenal insufficiency because it better simulates physiologic ACTH levels
- DHEA-S is a sensitive marker of adrenal reserve that may decline before cortisol abnormalities become apparent; it serves as an early indicator of HPA axis strain
- Levothyroxine should not be initiated in patients with concurrent cortisol deficiency without first addressing cortisol replacement, as thyroid hormone replacement increases cortisol clearance and can precipitate adrenal crisis
- Functional hypothalamic amenorrhea, HPA axis dysfunction, and subclinical thyroiditis frequently co-occur in the setting of chronic stress and energy deficit, representing a systemic neuroendocrine adaptation rather than isolated organ dysfunction

---

## Case 3: Insulin Resistance and Metabolic Optimization

### Patient Presentation
**Demographics:** 46-year-old male entrepreneur

**Chief Complaint:** "My doctor says I'm pre-diabetic, but I don't want to just wait until I need medications. I want to fix this now."

**History of Present Illness:**
The patient was found to have an HbA1c of 6.1% and fasting glucose of 112 mg/dL at his annual physical 3 months ago. His physician recommended lifestyle modifications and repeat testing in 6 months. Dissatisfied with the "wait and see" approach, he seeks a comprehensive metabolic optimization evaluation.

He reports a gradual 18 kg weight gain over 10 years, predominantly abdominal, now weighing 102 kg at 180 cm (BMI 31.5). He describes post-meal fatigue and "carb comas" after lunch, afternoon energy crashes requiring caffeine, and difficulty losing weight despite intermittent dieting attempts. He has noticed skin tags on his neck and axillae, and his wife has mentioned that the skin on the back of his neck appears darker.

He reports increased thirst and urination over the past year but attributed this to drinking more coffee. He snores loudly, and his wife reports observed apneas. He wakes unrefreshed despite 7-8 hours in bed. He has noticed declining cognitive sharpness, particularly in the afternoon, which concerns him as his business requires strategic decision-making.

**Past Medical History:**
- Pre-diabetes (recent diagnosis)
- Hypertension (borderline, not yet on medication)
- Non-alcoholic fatty liver disease (incidental finding on ultrasound 2 years ago)
- Gout (1 episode, 3 years ago)

**Medications:**
- None (declined metformin from PCP)
- Fish oil 1000 mg daily
- Multivitamin

**Social History:**
- Non-smoker, social alcohol (wine with dinner most nights, 10-14 units/week)
- Former college athlete (football), no current structured exercise
- High-stress business owner, works 50-60 hours/week
- Eats out frequently (business meals), large portions, high-carbohydrate diet
- Sleep: 7-8 hours in bed, unrefreshing, snoring

**Family History:**
- Father: Type 2 diabetes (diagnosed at 50, now on insulin), coronary artery disease
- Mother: Type 2 diabetes, obesity
- Paternal grandfather: Died of stroke at 62
- Two siblings: Both overweight, one with pre-diabetes

### Physical Examination
- **Vital Signs:** BP 138/86 mmHg, HR 78 bpm, RR 14, Temp 36.8°C, SpO2 96% RA, BMI 31.5, Waist circumference 108 cm, Waist-to-hip ratio 1.02
- **General:** Obese male with central adiposity, appears well
- **Skin:** Acanthosis nigricans on posterior neck and bilateral axillae (Grade 2), multiple skin tags on neck (>10), no striae
- **HEENT:** Mallampati class III
- **Cardiovascular:** Regular rate and rhythm, S4 gallop heard at apex, no murmurs
- **Abdomen:** Obese, non-tender, liver edge palpable 2 cm below costal margin
- **Extremities:** No edema, no xanthomas
- **Musculoskeletal:** Decreased muscle mass relative to body habitus

### Workup and Results

**Laboratory Studies:**
| Test | Result | Reference Range |
|------|--------|-----------------|
| Fasting glucose | 118 mg/dL | 70-100 mg/dL |
| Fasting insulin | 32.4 mU/L | 2.6-11.1 mU/L |
| HOMA-IR | 9.4 | < 1.7 (optimal) |
| HbA1c | 6.2% | < 5.7% (normal) |
| C-peptide (fasting) | 4.8 ng/mL | 0.8-3.1 ng/mL |
| 2-hour OGTT glucose | 186 mg/dL | < 140 normal, 140-199 IGT |
| 2-hour OGTT insulin | 248 mU/L | < 80 mU/L |
| Lipid panel | TC 232, LDL 142, HDL 32, TG 312 | TC <200, LDL <100, HDL >40, TG <150 |
| Apolipoprotein B | 148 mg/dL | < 90 mg/dL (optimal) |
| Lp(a) | 18 nmol/L | < 75 nmol/L |
| hs-CRP | 4.6 mg/L | < 1.0 mg/L optimal |
| Uric acid | 8.9 mg/dL | 3.5-7.2 mg/dL |
| AST | 52 U/L | < 40 U/L |
| ALT | 78 U/L | < 41 U/L |
| GGT | 92 U/L | < 60 U/L |
| Ferritin | 388 ng/mL | 12-300 ng/mL |
| HFE gene | Negative for C282Y and H63D | - |
| Adiponectin | 3.2 mcg/mL | 5-30 mcg/mL |
| Leptin | 42 ng/mL | 1-15 ng/mL (male) |
| Testosterone (total) | 312 ng/dL | 250-836 ng/dL |
| SHBG | 14 nmol/L | 10-57 nmol/L |
| Vitamin D | 24 ng/mL | 30-100 ng/mL |

**Imaging/Additional Studies:**
- Continuous glucose monitor (14-day data): Average glucose 128 mg/dL, time in range (70-140) 62%, glucose variability (CV) 32%, post-meal glucose peaks averaging 195 mg/dL with 60-minute time to peak
- FibroScan (liver elastography): CAP score 312 dB/m (steatosis grade S3, severe), liver stiffness 8.2 kPa (F2 fibrosis, moderate)
- Coronary artery calcium score: 82 Agatston units (above 75th percentile for age)
- Carotid intima-media thickness: 0.88 mm (elevated for age)
- Sleep study (home): AHI 22 events/hour (moderate OSA)
- DEXA body composition: Total body fat 38%, visceral adipose tissue area 182 cm2 (elevated), appendicular lean mass index borderline low

### Clinical Image

![Insulin resistance cascade and metabolic syndrome](case_03_image.jpg)

*Comprehensive diagram of the insulin resistance cascade showing the progression from visceral adiposity through hepatic steatosis, dyslipidemia, hyperinsulinemia, beta-cell exhaustion, and eventual type 2 diabetes, with interconnected pathways including inflammatory cytokines, adipokine imbalance, and cardiovascular risk amplification. Source: Educational illustration.*

### Diagnosis
**Severe Insulin Resistance (HOMA-IR 9.4) with Impaired Glucose Tolerance, Metabolic Syndrome (5/5 criteria met), Non-Alcoholic Steatohepatitis (NASH) with Stage F2 Fibrosis, Moderate Obstructive Sleep Apnea, and Subclinical Atherosclerosis**

**Key Diagnostic Criteria:**
- HOMA-IR 9.4 (severely insulin resistant; > 5.0 indicates marked resistance)
- Fasting hyperinsulinemia (32.4 mU/L) with elevated C-peptide indicating compensatory hyperinsulinemia
- Impaired glucose tolerance on OGTT (2-hour glucose 186 mg/dL) with massive insulin response (248 mU/L) demonstrating remaining but strained beta-cell capacity
- Metabolic syndrome (all 5 ATP III criteria): waist > 102 cm, TG > 150, HDL < 40, BP > 130/85, fasting glucose > 100
- NASH indicated by elevated transaminases with severe steatosis and F2 fibrosis on FibroScan
- Atherogenic dyslipidemia pattern: elevated TG, low HDL, elevated ApoB (small dense LDL pattern)
- Coronary artery calcium > 0 indicating established subclinical atherosclerosis

### Treatment Plan
1. **Pharmacotherapy for metabolic optimization:**
   - Metformin 500 mg daily, titrate to 1000 mg BID over 4 weeks (insulin sensitization, hepatoprotective, reduces hepatic glucose output)
   - GLP-1 receptor agonist: semaglutide 0.25 mg SC weekly, titrate to 1.0 mg weekly over 16 weeks (weight loss, cardiovascular risk reduction, potential NASH benefit)
   - Consider pioglitazone 15-30 mg daily for NASH (evidence for fibrosis regression) after discussing risk profile
   - Vitamin E 800 IU daily (evidence for NASH without diabetes, but limited in pre-diabetes; discuss with hepatologist)
2. **Cardiometabolic risk management:**
   - High-intensity statin: rosuvastatin 20 mg daily (CAC > 0 with elevated ApoB indicates treatment benefit regardless of LDL alone)
   - Icosapent ethyl (Vascepa) 2 g BID for TG > 150 with elevated cardiovascular risk
   - BP management: lisinopril 10 mg daily (target < 130/80 given metabolic syndrome)
3. **Dietary intervention (precision nutrition based on CGM data):**
   - Carbohydrate-controlled Mediterranean diet: 100-130 g carbohydrates/day, emphasizing low glycemic index sources
   - Protein target: 1.6 g/kg ideal body weight/day (130 g/day) to support lean mass preservation
   - Eliminate alcohol (directly contributes to hepatic steatosis, caloric excess, and uric acid elevation)
   - Meal sequencing: vegetables and protein first, carbohydrates last (CGM-guided strategy shown to reduce glucose spikes by 30-40%)
   - Time-restricted eating: 10-hour eating window (8 AM-6 PM)
4. **Exercise prescription:**
   - Resistance training 3-4x/week (large muscle groups, 8-12 reps, progressive overload) - resistance training improves insulin sensitivity via GLUT4 translocation independent of weight loss
   - Zone 2 aerobic training 150 min/week (brisk walking, cycling) targeting 60-70% max HR
   - Post-meal walks: 15-minute walk after each main meal (reduces post-prandial glucose by 20-30%)
5. **OSA treatment:** CPAP with compliance monitoring; untreated OSA worsens insulin resistance via sympathetic activation and intermittent hypoxia
6. **CGM-guided optimization:** Continue CGM for 3 months; target time in range > 85%, glucose variability CV < 25%, post-meal peaks < 140 mg/dL
7. **Peptide therapy consideration:** Discuss potential role of tesamorelin (GHRH analog) for visceral fat and NASH given evidence for hepatic fat reduction in clinical trials; referral to endocrinologist for evaluation
8. **Monitoring:** HbA1c, fasting insulin, lipid panel, and liver enzymes at 3 months; FibroScan at 12 months; CAC score repeat at 3-5 years; CGM review monthly for first 3 months

### Key Learning Points
- HOMA-IR and fasting insulin are more sensitive early markers of metabolic dysfunction than fasting glucose or HbA1c alone; a patient can have severe insulin resistance and hyperinsulinemia for 5-10 years before glucose values become overtly diabetic
- Continuous glucose monitoring in non-diabetic patients provides actionable data on individual glycemic responses to foods, meal timing, exercise, and sleep that cannot be captured by standard lab testing
- NAFLD/NASH is the hepatic manifestation of insulin resistance and is now the leading cause of liver disease worldwide; FibroScan allows non-invasive staging, and F2 fibrosis represents a critical decision point for aggressive intervention
- Apolipoprotein B is superior to LDL-C for cardiovascular risk assessment in insulin-resistant patients because it captures atherogenic particle number including small dense LDL, VLDL remnants, and IDL that are characteristic of the metabolic syndrome lipid phenotype
- The combination of early pharmacotherapy (metformin + GLP-1 RA), structured exercise (especially resistance training), dietary carbohydrate optimization, and OSA treatment can reverse insulin resistance and potentially prevent progression to type 2 diabetes even with strong family history