Common Pediatric Diseases and Disorders
A previously healthy 8-year-old girl is brought to the emergency department by worried parents. For the past two weeks, she's been drinking water constantly—"She finishes a gallon a day," her mother says. She's up multiple times at night to urinate, and despite eating more than usual, she's lost 10 pounds. Today, she's been vomiting and seems confused. Her breath has a strange, fruity odor. The glucometer reads "HI" (>600 mg/dL). This is diabetic ketoacidosis—and it's how about 30-40% of children with type 1 diabetes are diagnosed.
🦠 Understanding Type 1 Diabetes: When the Body Attacks Itself
The Autoimmune Process
Type 1 diabetes (T1D) is an autoimmune disease in which the body's immune system destroys the insulin-producing beta cells in the pancreatic islets of Langerhans. Without insulin, glucose cannot enter cells, accumulates in the bloodstream, and the body essentially starves despite high blood sugar.
Genetic Predisposition: Multiple genes involved (polygenic), HLA-DR3, HLA-DR4 strongest associations
Environmental Trigger (Unknown): Viral infections (enterovirus, coxsackie) suspected, dietary factors theorized
Immune Activation: Autoreactive T-cells attack beta cells, autoantibodies develop
Progressive Beta Cell Destruction: Occurs over months to years, clinical symptoms appear when 80-90% destroyed
📊 Autoantibodies in Type 1 Diabetes
- GAD-65: Glutamic acid decarboxylase
- IA-2: Islet antigen-2
- ZnT8: Zinc transporter 8
- Insulin autoantibodies (IAA)
Presence of 2+ antibodies predicts T1D development
The Metabolic Crisis: Without insulin → glucose can't enter cells → hyperglycemia → fat breakdown for energy → ketones produced → metabolic acidosis → severe dehydration → electrolyte imbalances → DKA
📊 Epidemiology: A Growing Problem
Incidence and Distribution
Key Epidemiological Facts
- Peak ages: 4-6 years and 10-14 years (puberty)
- Incidence: Increasing worldwide (3-5% per year)
- Prevalence: About 1 in 300 children by age 18
- Geographic variation: Highest in Finland, Sardinia, Northern Europe
Type 1 vs Type 2 Diabetes
- T1D: Autoimmune, absolute insulin deficiency, ketosis-prone
- T2D: Insulin resistance + relative deficiency, obesity-associated
- Note: Overlap exists—obese children can have T1D
🚨 Clinical Presentation: The Classic Triad and Beyond
The Classic Symptoms: "The 3 Ps"
Cardinal Symptoms
- Polyuria: Excessive urination, bedwetting in previously dry child
- Polydipsia: Excessive thirst, constant drinking
- Polyphagia: Excessive hunger despite weight loss
- Weight Loss: Unexplained, rapid (5-10+ pounds in weeks)
- Fatigue: Constant tiredness, poor school performance
Pathophysiology of Symptoms
- Polyuria: Glucose spills into urine → osmotic diuresis
- Polydipsia: Compensating for fluid losses
- Polyphagia: Cells "starving" without glucose entry
- Weight Loss: Breakdown of fat and muscle for energy
High-Yield Pearl: "Think diabetes in any child with polyuria, polydipsia, and weight loss." It's a classic presentation—don't miss it.
🆘 Diabetic Ketoacidosis (DKA): The Emergency Presentation
DKA Triad and Clinical Presentation
| Severity | pH | Bicarbonate | Mental Status |
|---|---|---|---|
| Mild | 7.25-7.30 | 15-18 mEq/L | Alert |
| Moderate | 7.0-7.24 | 10-14 mEq/L | Alert or drowsy |
| Severe | <7.0 | <10 mEq/L | Stupor or coma |
Clinical Presentation
- Early/Mild: Nausea, vomiting, abdominal pain
- Moderate: Kussmaul respirations, fruity breath, dehydration
- Severe: Altered mental status, severe dehydration, shock
Who Presents with DKA?
- 30-40% of new-onset T1D cases
- Younger children (especially <5 years) more likely
- Delayed diagnosis cases
- Lower socioeconomic status
- Ethnic minorities
Critical Pearl: "DKA abdominal pain is from the acidosis, not a surgical belly." Treat the DKA; pain resolves with treatment.
🔬 Diagnosis: Confirming the Suspicion
Diagnostic Criteria (ADA)
Diagnostic Criteria
Classic Symptoms PLUS Random Glucose ≥200 mg/dL
OR any one of:
- Fasting Glucose ≥126 mg/dL (no calories for 8+ hours)
- Oral Glucose Tolerance Test (OGTT) 2-hour Glucose ≥200 mg/dL
- Hemoglobin A1C ≥6.5%
In the presence of classic symptoms, ONE abnormal test sufficient. Without symptoms, need TWO abnormal tests on different days.
📊 Additional Testing at Diagnosis
Confirm Type 1
- Autoantibodies: GAD-65, IA-2, ZnT8, insulin autoantibodies
- C-peptide: Low or undetectable
Assess Complications/Comorbidities
- Hemoglobin A1C: Reflects average glucose
- Thyroid function: 17-30% have thyroid autoimmunity
- Celiac screen: 5-10% prevalence
- Lipid panel, creatinine, urinalysis
💊 Acute Management: DKA Protocol
DKA is a Medical Emergency Requiring ICU Care
Initial Assessment and Stabilization: ABCs, IV access, cardiac monitoring, neurological assessment
Fluid Resuscitation: 10-20 mL/kg 0.9% normal saline over 1 hour, replace deficit gradually over 48 hours
Insulin Therapy: Continuous IV insulin infusion 0.05-0.1 units/kg/hour after fluid bolus and potassium >3.3 mEq/L
Potassium Replacement: Total body potassium depleted, replace aggressively once insulin started
Monitoring: Hourly glucose and neurological status, electrolytes every 2-4 hours
Critical Rules: Avoid hypotonic fluids initially (cerebral edema risk). Avoid rapid glucose decline (50-100 mg/dL per hour goal). "Total body potassium is always low in DKA, even if serum potassium is normal."
🧠 Cerebral Edema: The Dreaded Complication
Leading Cause of DKA Death
Risk Factors
- Age <5 years
- New-onset diabetes
- Severe dehydration
- Low CO2 at presentation
- Rapid fluid administration
- Rapid decline in glucose
- Bicarbonate use
Clinical Signs (4-12 hours into treatment)
- Headache, altered mental status
- Bradycardia, increased BP
- Vomiting, incontinence
- Pupil changes, papilledema
- Posturing, respiratory arrest
🚨 Immediate Management
- Elevate head of bed 30 degrees
- Mannitol 0.5-1 g/kg IV OR Hypertonic saline 3% NaCl 2.5-5 mL/kg
- Reduce IV fluid rate
- Intubation if needed
- Head CT, neurosurgery consultation
Clinical Pearl: "Cerebral edema is the leading cause of DKA death." Watch for mental status changes 4-12 hours into treatment.
🔑 High-Yield Diabetes Summary - Part 1
| Aspect | Key Principles | Clinical Applications |
|---|---|---|
| Pathophysiology | Autoimmune beta cell destruction | Genetic predisposition + environmental trigger → immune activation |
| Clinical Presentation | Polyuria, polydipsia, polyphagia, weight loss | 30-40% present with DKA, especially younger children |
| Diagnosis | ADA criteria: symptoms + hyperglycemia | Autoantibodies confirm T1D, screen for comorbidities |
| DKA Management | Fluids, insulin, potassium, monitoring | Gradual correction, watch for cerebral edema |
| Cerebral Edema | Leading cause of DKA death | Early recognition, mannitol/hypertonic saline |