🦋 Radioactive Iodine Therapy Simulator

Graves' Disease vs Toxic Nodular Goiter

Same isotope, two very different gland biologies to dose for.

• 50–80%: Graves' 24h uptake (diffuse, uniform)
• 20–50%: TNG 24h uptake (patchy, nodule-driven)
• ~1%: Graves' prevalence (of US adults)
• >50 yrs: TNG typical age (older population)

Diffuse vs autonomous overactivity

Graves' drives the whole gland; nodules drive only themselves.

Why uptake pattern matters for dosing

Uneven nodular uptake means more isotope is needed overall.

Choosing the comparison framework

Same slider tools, diagnosis-specific dose ranges and outcomes.

Fixed Empiric Dose vs Calculated Dose

Clinicians pick a dosing philosophy before picking a number.

• Simple: Fixed dosing (standard mCi by diagnosis)
• Tailored: Calculated dosing (gland mass × uptake based)
• Lower dose: Conservative aim (fewer hypothyroid cases)
• Higher dose: Aggressive aim (fewer retreatments)

Fixed empiric approach

A standard activity is given regardless of gland size.

Calculated approach

Dose scales with measured gland volume and uptake percent.

The strategy slider

Conservative to aggressive spans the typical dosing range.

Typical mCi Ranges by Diagnosis

Toxic nodular goiter generally sits higher on the dose scale.

• 8–20 mCi: Graves' typical range (lower end common)
• 15–30 mCi: TNG typical range (higher end common)
• 8.0 days: Isotope half-life (I-131 physical decay)
• Oral capsule: Route (single outpatient dose)

Why nodular disease needs more activity

Non-uniform uptake means a larger total dose reaches nodules.

Reading the dose-range indicator

The marker shows where the chosen dose sits in range.

Practical dosing considerations

Gland size, symptom severity, and prior treatment all matter.

Cure, Retreatment, and Hypothyroidism Odds

Every dose choice reshapes three competing outcome probabilities.

• Higher: Low-dose retreatment (both diagnoses)
• Higher: High-dose hypothyroidism (especially Graves')
• Lower: TNG hypothyroid risk (normal tissue often spared)
• Higher: Graves' hypothyroid risk (diffuse gland ablated)

Reading the stacked bars

Each column splits into cure, retreatment, and hypothyroid segments.

How dose reshapes the split

Sliding toward aggressive shrinks retreatment, grows hypothyroidism.

Diagnosis changes the baseline

Nodular goiter keeps hypothyroid risk lower at any given dose.

Dose Selection Is a Clinical Balancing Act

There is no dose that maximizes cure while minimizing hypothyroidism.

• Tradeoff: Cure vs hypothyroid (inherent to I-131 dosing)
• Lifelong: Levothyroxine (if hypothyroidism results)
• Patient input: Shared decision (on acceptable risk)
• Context-based: No single "right" dose (diagnosis, size, preference)

Accepting the overshoot

Many clinicians favor higher doses to avoid repeat treatment.

When conservative dosing fits better

Younger patients may prioritize avoiding lifelong replacement.

Individualizing the choice

Diagnosis, gland size, and patient goals all shape the dose.

Placeholder: the "optimal" dose depends on which outcome a patient values most.

Dose strategy comparison at a glance