Table 2.

The subsyndromes in four phases of acute radiation syndrome^a

Syndrome	Signs and symptoms4
	Prodromal phase first 48 hoursb	Latent phase lasts up to a month	Manifest illness phase	Final outcome: survival or death
Gastrointestinal Occurs at doses between 5 Gy and 12 Gy	Nausea, vomiting, diarrhea, anorexia, hemorrhage, weakness through denuded areas Loss of absorptive capacity Increased intensity 4–8 hours	Tiredness and anorexia	Vomiting and fever; progression of bloody diarrhea to shock and death or treatment	Radiation 8–30 Gy dose range cause death from gastrointestinal syndrome
Hematologic High dose between 2–3 Gy and 8 Gy. Low dose (<2 Gy) radiation	Often asymptomatic Some fatigue, fever, and bacteremia	Lymphopenia Granulocytopenia Thrombocytopenia	Neutropenia (ANC < 0.5)c Fever, sepsis, hemorrhage, purpura, electrolyte disturbances, and epilation	Agranulocytosis irresponsive to GM-CSF after first cell cycle
Central nervous system	No specific signs and symptoms Unspecific fatigue, malaise, anorexia, and drowsiness Not consistently correlated to exposed dose	Latency up to a month Asymptomatic phase except for tiredness and weakness	Headache Impaired cognition, disorientation, seizure, tremor, ataxia Grand mal seizures	Irreversible brain damage secondary to continuous cramps
Pulmonary dysfunction	Acute radiation pneumonitis Cough, shortness of breath ALId with inflammatory coagulation activation	Pulmonary edema Pneumonitis	ARDSe Intubation and mechanical ventilation Severe pneumonia Lung fibrosis after 14–30 days from first exposure	Absolute respiratory insufficiency Severely reduced oxygen transport capacity

^aNotes: Induced by a radiation dose of ≥1 Gy;²,⁴

^bonset within the first hour of explosive bloody diarrhea signals a fatal outcome. Appearance during the first 2–3 hours indicates a high dose. Onset between 6–12 hours and termination within 24 hours suggest a sublethal (1–2 Gy) dose. Gastrointestinal symptoms must be documented at the initial and each subsequent examination, and differentiated from a normal stress/anxiety response;¹¹

^cgrowth factors should be started promptly and continued until ANC >1000;⁸,⁹

^dinfiltrates on chest film and moderately reduced oxygen transport (PaO₂/FiO₂ < 300 mmHg);

^econfluent infiltrates on chest film and severely reduced oxygen transport capacity (PaO₂/FiO₂ < 200 mmHg).

Abbreviations: ALI, acute lung insufficiency; ANC, absolute neutrophil count; ARDS, acute respiratory distress syndrome; FiO₂, fraction of inspired oxygen in a gas mixture; GM-CSF, granulocyte-macrophage colony-stimulating factor; PaO₂, partial pressure of oxygen in the blood.