Diabetes ketoacidosis Lyme disease explain them
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Diabetic Ketoacidosis (DKA)
Definition
DKA is defined by three fundamental biochemical features (the classic triad):
- Hyperglycemia (or a known history of diabetes)
- Ketonuria (urinary ketones ≥2+ or serum ketones ≥3.0 mmol/L)
- Acidosis (arterial or venous pH <7.3)
- Goldman-Cecil Medicine
Pathophysiology
DKA results from combined insulin deficiency + excess counter-regulatory hormones (glucagon, cortisol, catecholamines, growth hormone). This hormonal imbalance:
- Drives delivery of substrates from muscle (amino acids, lactate, pyruvate) and adipose tissue (free fatty acids, glycerol) to the liver
- The liver converts these to glucose and ketone bodies (β-hydroxybutyrate, acetoacetate, acetone)
- Glucose and ketones flood the circulation faster than they can be used
- Hyperglycemia causes osmotic diuresis → dehydration + electrolyte loss
- Dehydration causes hemoconcentration → worsening hyperglycemia and hyperosmolality in a vicious cycle
The three ketone bodies are:
- β-Hydroxybutyrate - the predominant one (often falsely underdetected by nitroprusside strips)
- Acetoacetate
- Acetone
Precipitating Causes
| Most Common | Other |
|---|---|
| Infections | Stroke, pulmonary embolism |
| Inadequate insulin / nonadherence | Acute pancreatitis |
| New-onset diabetes (type 1) | Cushing syndrome, thyrotoxicosis |
| Acute coronary syndrome | Severe burns |
| Unknown | Drugs: corticosteroids, SGLT-2 inhibitors, clozapine, olanzapine, cocaine, lithium, thiazides |
An important behavioral cause: some younger patients omit insulin deliberately to lose weight or draw attention to a dysfunctional home situation.
Clinical Features
Onset is typically over hours to days with:
- Progressive polyuria, polydipsia, weakness, lethargy, nausea, anorexia
- Nonspecific abdominal pain (can mimic acute abdomen)
- Reduced GI motility or paralytic ileus
- Physical signs from dehydration: dry skin/mucous membranes, tachycardia, orthostatic hypotension, reduced JVP
- Kussmaul breathing - deep, rapid respirations (compensatory response to metabolic acidosis)
- Depressed mental function to frank coma in severe cases
Diagnosis & Labs
| Finding | Value |
|---|---|
| Blood glucose | Variable; normal to >1000 mg/dL (55.5 mmol/L) |
| Serum bicarbonate | <18 mmol/L |
| pH | 7.20-7.30 (mild) to <7.00 (severe) |
| Anion gap | Elevated, proportional to HCO3 drop |
| Sodium | Often low (osmotic water shift) |
| Potassium | May be normal, high, or low at presentation - but always total body depleted |
| WBC | Elevated (from acidosis itself, not necessarily infection) |
| Hematocrit | Elevated (hemoconcentration) |
Key pitfall with ketone testing: Nitroprusside strips only react with acetoacetate. β-Hydroxybutyrate (the major ketone in DKA) does NOT react - so strips can falsely underestimate the severity of ketoacidosis. After insulin starts, β-hydroxybutyrate converts to acetoacetate, so strips may appear to show worsening ketosis even as the patient improves. Point-of-care capillary ketone monitors are now preferred.
Treatment
Treatment has four pillars:
1. Fluid Replacement
- Start with 0.9% NaCl (even if serum osmolality is high, since normal saline is still relatively hypotonic)
- Rate: 2-4 liters in the first 2-4 hours in DKA
- Fluid losses of 5-10 L are common; electrolyte losses include sodium 5-10 mmol/kg and potassium up to 7 mmol/kg
2. Potassium Replacement
- Even if K+ is initially elevated (due to acidosis shifting K+ extracellularly), it will fall sharply once insulin is given
- Hold K+ replacement if K+ >5.5 mEq/L; but begin when K+ is ≤5.5 and falling
- A low initial K+ signals profound total body depletion and requires prompt IV replacement before insulin
3. Insulin
- IV insulin to halt ketogenesis and reduce glucose
- Glucose replacement (5% dextrose) should be added to the infusion once blood glucose falls to avoid hypoglycemia
4. Treat the Precipitant
- Identify and treat underlying infection, ACS, or other trigger
Prognosis: Despite aggressive treatment, mortality is approximately 4% for DKA and up to 20% for hyperosmolar hyperglycemic state (HHS). Death is associated with extremes of age, comorbidities, and severity of the precipitating event.
Lyme Disease
Causative Agent & Epidemiology
Lyme disease is caused by spirochetes of the Borrelia burgdorferi sensu lato complex:
- B. burgdorferi sensu stricto - United States
- B. garinii - Europe/Asia; principal cause of Lyme neuroborreliosis
- B. afzelii - Europe/Asia; associated with acrodermatitis chronica atrophicans
Transmission: By hard ticks (family Ixodidae):
- Ixodes scapularis - eastern and midwestern US
- I. pacificus - western US
- I. ricinus - Europe
- I. persulcatus - Eastern Europe and Asia
Reservoirs: Mice, deer, ticks. Seasonal peak: June-July (nymph feeding stage).
US geography: Most cases from two foci - Northeast/Mid-Atlantic states (Maine to Virginia) and Upper Midwest (Minnesota, Wisconsin).
The tick must be attached for >24 hours to transmit disease in the US.
Clinical Stages
Stage 1 - Early Localized (Days to weeks after bite)
The hallmark is erythema migrans (EM):
- Begins as a small red macule/papule at the bite site 3-32 days (median 7) after the bite
- Gradually expands outward to an annular (bull's-eye) rash, median diameter 15 cm (range 3-68 cm)
- Border is slightly raised, warm, red to bluish-red, no scale
- Center may clear (classic bull's-eye) or remain red/indurated/vesicular
- Accompanied by burning in 50% of patients; rarely itchy
- Common sites: legs, groin, axilla
Only ~50% of patients recall the tick bite.
Here is the classic appearance of erythema migrans:
Erythema migrans on the upper back - Andrews' Diseases of the Skin
Stage 2 - Early Disseminated (Weeks to months)
- Musculoskeletal: Migratory arthralgia, myalgia
- Neurologic (Lyme neuroborreliosis): Stiff neck, headache, meningitis, cranial nerve palsies (Bell palsy is classic), radiculopathy, peripheral neuropathy, cognitive deficits, vestibular neuronitis
- Cardiac: Fluctuating degrees of AV block or complete heart block (most often in young men), lasting 3 days to 6 weeks; dilated cardiomyopathy in European cases
- Skin: Multiple secondary EM lesions
In Europe: Bannworth syndrome - focal radicular pains + lymphocytic meningitis + cranial nerve paralysis.
Stage 3 - Late Disseminated (Months to years)
- Chronic arthritis - especially of the knees; ~10% of untreated US patients; leads to severe disability in half
- Acrodermatitis chronica atrophicans (ACA) - almost exclusively in Europe (B. afzelii); diffuse reddish-blue, paper-thin atrophic skin on extremities; progressive and never fully involutes
- Neurologic sequelae
Diagnosis
- Clinical: Erythema migrans is the most sensitive evidence of early infection - diagnose clinically without waiting for serology
- Serology: Two-tier testing:
- Screening: ELISA (89% sensitive, 72% specific)
- Confirmation: Western blot (IgM: 2/3 bands positive; IgG: 5/10 bands positive)
- Serology limitations: Only 27% positive if symptoms <7 days, 41% at 7-14 days, 88% if >2 weeks
- PCR: Specific but insensitive; not widely available
- False positives occur in: syphilis, yaws, pinta, leptospirosis, relapsing fever, infectious mononucleosis, autoantibody-related diseases (note: VDRL is negative in B. burgdorferi infection)
Treatment
| Situation | Treatment |
|---|---|
| Early localized/disseminated (adults) | Doxycycline 100 mg twice daily x 21 days (first choice; also covers Ehrlichia) |
| Adults (alternative) | Amoxicillin 500 mg TID x 21 days OR Cefuroxime axetil 500 mg BID x 21 days |
| Children <9 years | Amoxicillin 20 mg/kg/day in divided doses |
| Pregnant (localized) | Amoxicillin |
| Pregnant (disseminated) / Immunodeficient | IV Penicillin G or IV Ceftriaxone |
| Carditis / Neurologic / Arthritic involvement | More aggressive regimens; parenteral antibiotics often indicated |
Prevention:
- Avoid tick-infested areas; inspect for ticks after outdoor activity
- Nymphs are tiny ("the freckle that moves") - harder to spot
- Post-exposure prophylaxis: Single dose of doxycycline 200 mg within 72 hours of a bite from a partially engorged I. scapularis in a high-incidence area is 87% effective
Key Differences at a Glance
| Feature | DKA | Lyme Disease |
|---|---|---|
| Cause | Insulin deficiency + counter-regulatory excess | Borrelia burgdorferi spirochete infection |
| Transmission | Metabolic / endocrine | Tick bite (Ixodes spp.) |
| Key sign | Kussmaul breathing, fruity breath, altered mental status | Erythema migrans (bull's-eye rash) |
| Key lab | pH <7.3, elevated ketones, anion gap acidosis | ELISA + Western blot serology |
| Acute treatment | IV fluids, insulin, electrolyte replacement | Doxycycline (oral) |
| Mortality | ~4% (DKA), up to 20% (HHS) | Low if treated early; complications if untreated |
Sources: Goldman-Cecil Medicine (DKA); Andrews' Diseases of the Skin and Medical Microbiology 9e (Lyme disease)
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