L2A0A3 - Obstetric Notation Explained

Note: When two "A" values appear, the first A typically refers to induced (elective) abortions, and the second A refers to spontaneous abortions (miscarriages).

Context within the Full Obstetric Notation System

• G - Gravida (total number of pregnancies)
• T - Term deliveries (at 37+ weeks)
• P - Preterm deliveries (20-36 weeks)
• A - Abortions/losses (before 20 weeks)
• L - Living children

Putting It Together

• 2 living children
• No induced abortions
• 3 spontaneous abortions (miscarriages)

L2 A0 A3 - Leprosy WHO Disability Grading

*Some WHO versions use a 0-2 scale for eyes (Grade 2 = severe visual loss/blindness), while others extend to Grade 3.

WHO Leprosy Disability Grading Scale

• Grade 0 - No disability; no anesthesia, no visible deformity
• Grade 1 - Loss of protective sensation (anesthesia) but no visible deformity
• Grade 2 - Visible deformity or damage (ulcers, clawing, contractures, foot drop, lagophthalmos)

Important Note

Thyroxine in Congenital Nephrotic Syndrome (CNS)

Why Is Thyroxine Needed?

Purpose of Thyroxine (Levothyroxine) Supplementation

Key Clinical Points

• Higher-than-normal doses are required because the supplemented thyroxine is also being lost in the urine continuously. Doses as high as 17.5 mcg/kg/day (compared to the usual 10-15 mcg/kg/day in standard congenital hypothyroidism) may be needed.
• Frequent monitoring of TFTs (TSH + free T4) is essential, as levels fluctuate with disease activity and albumin infusions.
• Dose adjustment is needed in both directions - increases during active nephrotic syndrome, reductions during remission.
• If the patient undergoes bilateral nephrectomy (done to stop protein loss before renal transplantation), thyroid function can normalize and thyroxine may be tapered/stopped.
• Levothyroxine is typically started early (even in the neonatal period) once abnormal TFTs are detected, since the Guthrie (newborn screening) card will be negative - the baby's thyroid gland is structurally normal.

Summary

In CNS, thyroxine (levothyroxine) is given as replacement therapy for urinary-loss-induced hypothyroidism - not because the thyroid gland is diseased, but because the binding proteins that carry T4 in the blood are being lost through the damaged glomeruli. Without replacement, infants face serious risks of brain damage, growth failure, and cardiovascular compromise.

Management & Treatment of Neonatal Jaundice

Overall Goal

Step 1 - Initial Assessment

• Jaundice within first 24 hours of life
• Elevated direct (conjugated) bilirubin - always pathological
• TSB rising faster than expected or approaching exchange levels
• Jaundice beyond 3 weeks of age
• Sick-appearing infant

• TSB (total serum bilirubin) - fractionated (direct + indirect)
• Transcutaneous bilirubin (TcB) - for screening in well infants >24 hrs
• FBC + peripheral smear
• Direct Coombs (DAT) test - for isoimmune haemolysis
• Blood group (infant and mother)
• Blood glucose, septic screen if sick

Step 2 - General (Supportive) Measures

• Encourage feeding (breast or formula) - stimulates gut motility, reduces enterohepatic circulation of bilirubin
• Adequate hydration - prevents dehydration-related worsening
• Do NOT supplement with water - does not reduce bilirubin and can cause hyponatraemia
• Treat any underlying cause (infection, haemolysis, metabolic disorder)

Step 3 - Phototherapy

Mechanism

When to Start

• Isoimmune haemolytic disease (ABO/Rh incompatibility)
• G6PD deficiency
• Asphyxia / significant lethargy
• Temperature instability / sepsis / acidosis
• Albumin <3.0 g/dL

Types of Phototherapy

Monitoring

• Check TSB every 4-6 hours initially; extend intervals as bilirubin stabilises
• Discontinue when TSB falls sufficiently below the threshold for the infant's age/risk
• Rebound bilirubin check 12-24 hrs after stopping phototherapy (especially in haemolytic disease)

Step 4 - Intravenous Immunoglobulin (IVIG)

• Dose: 500 mg/kg IV over 2 hours
• Indication: TSB rising rapidly despite intensive phototherapy, or within 2-3 mg/dL of exchange transfusion threshold
• Mechanism: Blocks Fc receptors on macrophages, reducing red blood cell destruction and slowing rate of bilirubin rise
• May be repeated once if needed
• Can reduce the need for exchange transfusion in haemolytic disease

Step 5 - Exchange Transfusion

When to Perform

• Signs of acute bilirubin encephalopathy are present (hypertonia, arching, retrocollis, opisthotonos, fever, high-pitched cry)
• TSB is 5 mg/dL (85 µmol/L) above the exchange transfusion threshold line
• TSB continues to rise or remains above threshold despite intensive phototherapy

Procedure (Double-Volume Exchange)

• Uses double the infant's blood volume (~160-200 mL/kg)
• Done via umbilical vein catheter
• Removes sensitised RBCs, bilirubin, and maternal antibodies
• Replaces with O-negative, CMV-negative irradiated packed red cells in fresh frozen plasma

Risks

• Thrombocytopenia, electrolyte imbalance (hypocalcaemia, hyperkalaemia)
• Infection, air embolism, necrotising enterocolitis
• Cardiac arrhythmia, mortality (~0.5-1%)

Step 6 - Additional/Special Treatments

Summary Algorithm

Neonatal Jaundice
       ↓
Measure TSB + identify risk factors
       ↓
     Conjugated?  →  YES → Investigate and treat cause (biliary atresia, infection, metabolic)
       ↓ NO
Plot TSB on AAP nomogram
       ↓
Below phototherapy threshold → Monitor + encourage feeding
       ↓
Above phototherapy threshold → Start PHOTOTHERAPY
       ↓
Haemolytic disease + rising rapidly → Add IVIG
       ↓
Above exchange threshold or ABE signs → EXCHANGE TRANSFUSION

Crigler-Najjar Syndrome Type II - Phenobarbital Mechanism & Management

Background - The Two Types Compared

Why Does Phenobarbital Work in Type II?

The Key Difference

Mechanism of Phenobarbital

1. Binds to the promoter region of UGT1A1 upon activation by phenobarbital
2. Upregulates transcription of the UGT1A1 gene
3. Increases the amount of UGT1A1 enzyme protein in hepatocytes
4. The larger pool of (albeit less-efficient) enzyme conjugates more bilirubin
5. Conjugated bilirubin (water-soluble) is then excreted into bile normally

Clinical Use of Phenobarbital in Type II

Phenobarbital as a Diagnostic Tool

• No response → strongly suggests Type I → plan for liver transplantation
• Clear bilirubin reduction → confirms Type II → continue phenobarbital long-term

Additional Management in Type II

• Phototherapy - may be needed during acute bilirubin rises (intercurrent illness, fasting, surgery)
• Avoid triggers that worsen hyperbilirubinemia: fasting, dehydration, certain drugs (rifampicin, cyclosporine, valproate which compete with or inhibit UGT)
• Liver transplant - not usually needed in Type II but reserved for severe refractory cases
• Gene therapy - under investigation for both Type I and II (AAV-mediated UGT1A1 delivery)

Key Point Summary

Phenobarbital works in Crigler-Najjar Type II because the enzyme is reduced, not absent. By inducing UGT1A1 gene transcription via the CAR nuclear receptor, phenobarbital amplifies the residual enzyme pool enough to significantly lower bilirubin and prevent kernicterus - allowing these patients to live a normal lifespan, which sharply contrasts with the fatal outcome of untreated Type I.

Other Enzyme Inducers That Work in Crigler-Najjar Type II

Documented UGT1A1 Inducers in Type II

Why These Work - Receptor Pathways

Phenobarbital  → CAR activation → UGT1A1 gene transcription ↑
Clofibrate     → PPARα activation → UGT1A1 gene transcription ↑
Rifampicin     → PXR activation → UGT1A1 gene transcription ↑
                                       ↓
                              More UGT1A1 enzyme
                                       ↓
                         More bilirubin conjugated → excreted
                                       ↓
                              Serum bilirubin falls

Important Caveat - HNF-1α Promoter Mutations

• The promoter cannot be activated by CAR, PXR, or PPARα ligands
• Neither phenobarbital nor any other inducer works
• This is why genetic testing is important - if an HNF-1α site mutation is found, inducers should not be used and alternative management is required

Broader Pharmacological Treatments in Type II

Practical Bottom Line

Treatment of Acinetobacter baumannii Infections

Key Principles

• Treatment difficulty stems from: distinguishing colonization vs true infection, and extensive multidrug resistance
• Empirical therapy should be based on local epidemiology and patient's known colonization status
• Definitive therapy must be guided by antimicrobial susceptibility testing (AST)
• Always obtain Infectious Diseases consultation - proven to reduce mortality

Step 1 - Classify by Resistance Profile

Treatment by Susceptibility

A. Carbapenem-Susceptible Strains

B. Carbapenem-Resistant A. baumannii (CRAB) - 2024 IDSA Preferred Regimen

First-Line (Preferred):

Clinical evidence: RCT (n=125 CRAB patients) showed 19% 28-day mortality with sulbactam-durlobactam vs 32% with colistin - lower nephrotoxicity too. - Harrison's 22E, p.1340

Alternative (When sulbactam-durlobactam unavailable):

High-dose sulbactam rationale: increases binding to PBP2 and PBP3 targets to optimise cell wall synthesis inhibition.

C. Novel Agent: Cefiderocol

Drug Activity Summary vs Resistant Organisms

Special Site Considerations

Resistance Mechanisms (Why This Bug Is So Hard to Treat)

• OXA-type carbapenemases (OXA-23, OXA-40, OXA-58) - most common CRAB mechanism
• ADC (Acinetobacter-derived cephalosporinase) - intrinsic AmpC β-lactamase
• ESBL production
• Efflux pumps (AdeABC, AdeFGH)
• Porin loss (OmpA downregulation)
• Biofilm formation on devices

Quick Reference - IDSA 2024 Algorithm

A. baumannii infection confirmed
          ↓
    Susceptibility testing
          ↓
Carbapenem-susceptible? → YES → Ampicillin-sulbactam ± carbapenem
          ↓ NO
        CRAB
          ↓
Sulbactam-durlobactam available? → YES → Sulbactam-durlobactam + imipenem
          ↓ NO
High-dose Amp-Sulbactam + (Polymyxin B or Tigecycline or Minocycline or Cefiderocol)
          ↓
Reassess 48-72h; adjust per cultures + clinical response