The term acute radiation syndrome (ARS) is used to describe the onset and progression of symptoms after exposure to ionizing radiation, and the clinical course is divided into four phases [1] [2]:

• Prodromal phase - Gastrointestinal complaints, such as nausea, vomiting, diarrhea, weakness and weight loss due to profound damage of the intestinal mucosa are main features. In doses of 1-2 grays (Gy), symptoms appear two or more hours after exposure, whereas very severe and lethal exposures (6-8 and > 8 Gy, respectively) produce symptoms in less than 30 minutes [3]. Headaches, altered consciousness, and fever may be observed as well [3]. Cutaneous radiation syndrome (CRS) is the term used to describe skin-related changes that range from mild erythema in this period to more severe lesions encountered later on [4].
• Latent phase - Myelosuppression is the hallmark of latent phase, developing between 1 and 5 weeks after initial exposure, again depending on the severity of exposure [5]. Lymphopenia, granulocytopenia, and thrombocytopenia are most prominent findings, accompanied by anorexia and generalized fatigue [1]. Pneumonitis, pulmonary edema, and varying degrees of skin depilation are other notable symptoms [1] [3].
• Illness manifestation phase - Considered as the "critical phase" of radiation exposure, it is characterized by the dose-dependent occurrence of impaired central nervous system activity (headaches, impaired cognitive function, disorientation, ataxia, and convulsions), the progression of vomiting and fever to life-threatening bloody diarrhea, cardiovascular collapse, and shock. Additionally, acute respiratory distress syndrome (ARDS), purpura, electrolyte disturbances and infection due to severe myelosuppression that may lead to sepsis are frequently reported [1] [2].
• Final outcome - Patients either recover from the deleterious effects induced by radiation, or suffer from fatal organ damage, and the most significant predictors of outcome are the dosage received and heterogeneity of dosage, as either single or multiple organs may be affected [3].

• Fatigue

  They presented with run-down symptoms of neck strain associated with throbbing headache, irritability, loss of appetite, fatigue, memory difficulties, and numbness of extremities. [ncbi.nlm.nih.gov]

  Later symptoms, which may last hours or months, include loss of appetite, fatigue, fever, nausea, vomiting, diarrhea and possibly even seizures, coma and death. Radiation poisoning also usually causes skin damage. [healthland.time.com]

  The leading causes of most of those early deaths were disruption to the smooth operation of hospitals, the exacerbation of pre-existing health problems, and the transfer trauma or general 'mental fatigue' from dramatic changes in life situation. [world-nuclear.org]

  Exposure to small doses of radiation over time is associated with changes in blood chemistry, nausea, burns, fatigue, vomiting, hair loss, diarrhea and the development of cancer. 1 Exposure to high doses of radiation has also been associated with damage [itnonline.com]

  Lymphopenia, granulocytopenia, and thrombocytopenia are most prominent findings, accompanied by anorexia and generalized fatigue. Pneumonitis, pulmonary edema, and varying degrees of skin depilation are other notable symptoms. [symptoma.com]

• Anemia

  Anemia develops slowly, because preexisting RBCs have a longer life span than WBCs and platelets. Survivors have an increased incidence of radiation-induced cancer, including leukemia. [merckmanuals.com]

  Some patients may also present with autoimmune cytopenia (anemia and thrombocytopenia). Patients share several clinical features with Nijmegen breakage syndrome and LIG 4 deficiency (see these terms). [orpha.net]

  On July 4, 1934, Marie Curie died of aplastic anemia, a blood disease that often results from getting too much radiation. [web.archive.org]

• Rigor

  […] licensing Supervision of personnel Use of dosimetry badges Training or certification Dental office design and radiation shielding Record keeping Equipment Radiographic training requirements for dental office personnel frequently differ from and are less rigorous [ada.org]

  […] the least common among people with radiation-induced hypopituitarism.[35] Changes in prolactin-secretion is usually mild, and vasopressin deficiency appears to be very rare as a consequence of radiation.[35] Radiation therapy accidents[edit] There are rigorous [en.wikipedia.org]

• Chills

  CHILL. Refrigerate food promptly. For more information on food irradiation and other food safety issues, contact USDA's Meat and Poultry Hotline at 1-888-MPHotline (1-888-674-6854) or visit www.fsis.usda.gov. [ Top of Page ] [web.archive.org]

• Nausea

  The first symptoms of ARS are typically nausea, vomiting and diarrhea. These symptoms, the CDC says, start within minutes to days after the exposure, and can last for minutes or days. [healthland.time.com]

  Some examples of the symptoms seen in radiation sickness include nausea, skin burns, hair loss and reduced organ function. In severe cases, exposure to a large amount of radiation can even cause death. [news-medical.net]

  Early gastrointestinal effects such as nausea or vomiting may occur after single exposures of 1000 mSv or more (100 rads or cGy), and hematopoietic marrow suppression will occur after single doses of 3000 mSv or more. [atlasofscience.org]

  Effects of Whole-Body Irradiation From External Radiation or Internal Absorption Phase of Syndrome Feature Dose Range (Gy)* ,† 1–2 2–6 6–8 8–30 30 Prodrome Incidence of nausea and vomiting 5–50% 50–100% 75–100% 90–100% 100% Time of onset of nausea and [merckmanuals.com]

• Vomiting

  Median doses cause initial anorexia, lethargy and vomiting then normality for several weeks followed by vomiting, nasal discharge, dysentery, recumbency, septicemia and a profound pancytopenia. Death is the most common outcome. [medical-dictionary.thefreedictionary.com]

  The first symptoms of ARS are typically nausea, vomiting and diarrhea. These symptoms, the CDC says, start within minutes to days after the exposure, and can last for minutes or days. [healthland.time.com]

  vomiting after exposure 2–6 h 1–2 h 10–60 min 10 min Minutes Duration of nausea and vomiting 24 h 24–48 h 48 h 48 h N/A (patients die in 48 h) Severity and incidence of diarrhea None None to mild ( 10%) Moderate to Severe ( 10%) Severe ( 95%) Severe [merckmanuals.com]

  Early gastrointestinal effects such as nausea or vomiting may occur after single exposures of 1000 mSv or more (100 rads or cGy), and hematopoietic marrow suppression will occur after single doses of 3000 mSv or more. [atlasofscience.org]

  External contamination is performed by surveying the skin, while internal contamination requires sampling of the ears, the mouth, as well as urine, feces and vomit. [symptoma.com]

• Diarrhea

  High doses cause intense diarrhea and dehydration and extensive skin necrosis. [medical-dictionary.thefreedictionary.com]

  The first symptoms of ARS are typically nausea, vomiting and diarrhea. These symptoms, the CDC says, start within minutes to days after the exposure, and can last for minutes or days. [healthland.time.com]

  However, some prodromal symptoms (eg, nausea, vomiting, diarrhea, tremors) are nonspecific, and causes other than radiation should be considered. [merckmanuals.com]

  The symptoms of ARS include headache and diarrhea. They usually start within hours. Those symptoms will go away and the person will seem healthy for a little while. But then they will get sick again. [nlm.nih.gov]

• Abdominal Pain

  In some emergency departments, an increasingly large number of patients with abdominal pain or headache are evaluated with CT scanning. X-rays (including CT scans) should be ordered judiciously. [emedicine.medscape.com]

  Extensive radiation to the abdomen (for lymph node, testicular, or ovarian cancer) can lead to chronic ulcers, scarring, and narrowing or perforation of the intestine, causing symptoms such as abdominal pain, vomiting, vomiting blood, and dark, tarry [merckmanuals.com]

• Xerostomia

  It prevents xerostomia in patients undergoing radiation therapy. [merckmanuals.com]

  Dry mouth (xerostomia) and dry eyes (xerophthalmia) can become irritating long-term problems and severely reduce the patient's quality of life. [en.wikipedia.org]

• Blister

  […] similar to a sunburn). 10,000 mSvor more can cause a breakdown of the intestinal lining, leading to internal bleeding, which can lead to illness and death when the dose is to the abdomen. 15,000 mSvor more locally to the skin can cause skin reddening and blistering [radiationanswers.org]

  […] serotonin receptor antagonist when suspected exposure is >2 Gy (↓) Loperamide, as needed for control of diarrhea (↓) Cutaneous Topical class II–III corticosteroids, topical antibiotics, and topical antihistamines applied to radiation burns, ulcer, or blisters [merckmanuals.com]

• Alopecia

  They also presented with alopecia areata which is felt to be causally linked to the radiation exposure. [ncbi.nlm.nih.gov]

• Throbbing Headache

  They presented with run-down symptoms of neck strain associated with throbbing headache, irritability, loss of appetite, fatigue, memory difficulties, and numbness of extremities. [ncbi.nlm.nih.gov]

Physicians must be careful when interpreting symptoms, as gastrointestinal and central nervous system complaints are nonspecific and may arise in a myriad of conditions. For this reason, patient history is the vital component of the diagnostic workup. The detailed information regarding the onset of symptoms, potential exposure to radioactive substances at the workplace, as well as presence of similar findings in other coworkers is vital in making a presumptive diagnosis [6]. The use of a Geiger-Muller probe attached to a Geiger counter to inspect patients for contamination is pivotal for confirming radiation exposure, and the entire body should be examined [6]. External contamination is performed by surveying the skin, while internal contamination requires sampling of the ears, the mouth, as well as urine, feces and vomit [6]. Laboratory studies should include complete blood counts (CBC) performed on a daily basis after admission, with a particular emphasis on total lymphocyte count, which is considered to be one of the most valid indicators of the dose of radiation received [6]. If a total lymphocyte count is > 1500/mL, the radiation dose is expected to be around 0.4 Gy, and the chance of survival is very high, whereas counts of < 500/mL indicate exposure to > 4 Gy and carry a poorer prognosis [6]. A lymphocyte count of < 100/mL is universally fatal [6]. In addition to lymphocyte count, serum amylase, and C-reactive protein (CRP) levels should be evaluated, as they are elevated in proportion to the dose received [3] [6]. In the setting of profound skin changes, procedures such as bone scintigraphy, capillary microscopy and nuclear magnetic resonance imaging should be performed, if possible [4].

1. Heslet L, Bay C, Nepper-Christensen S. Acute radiation syndrome (ARS) – treatment of the reduced host defense. Int J Gen Med. 2012;5:105-115.
2. Longo DL, Fauci AS, Kasper DL, Hauser SL, Jameson J, Loscalzo J. eds. Harrison's Principles of Internal Medicine, 18e. New York, NY: McGraw-Hill; 2012.
3. Macià i Garau M, Lucas Calduch A, López EC. Radiobiology of the acute radiation syndrome. Rep Pract Oncol Radiother. 2011;16(4):123-130.
4. Peter RU, Gottlöber P. Management of cutaneous radiation injuries: diagnostic and therapeutic principles of the cutaneous radiation syndrome. Mil Med. 2002;167(2):110-112.
5. Dörr H, Meineke V. Acute radiation syndrome caused by accidental radiation exposure - therapeutic principles. BMC Med. 2011;9:126.
6. Porter RS, Kaplan JL. Merck Manual of Diagnosis and Therapy. 19th Edition. Merck Sharp & Dohme Corp. Whitehouse Station, N.J; 2011.