The host immune response involves cytotoxic (CD8-positive) T cells against infected B lymphocytes, resulting in enlarged, atypical lymphocytes (Downey cells).When the infection is acute (recent onset, instead of chronic), heterophile antibodies are produced.Cytomegalovirus, adenovirus and Toxoplasma gondii (toxoplasmosis) infections can cause symptoms similar to infectious mononucleosis, but a heterophile antibody test will test negative and differentiate those infections from infectious mononucleosis.Mononucleosis is sometimes accompanied by secondary cold agglutinin disease, an autoimmune disease in which abnormal circulating antibodies directed against red blood cells can lead to a form of autoimmune hemolytic anemia. The cold agglutinin detected is of anti-i specificity. Diagnosis
Diagnostic modalities for infectious mononucleosis include:

Persons age, with highest risk at 10 to 30 years. Medical history, such as close contact with other people with infectious mononucleosis, and the presence and time of onset of "mononucleosis-like symptoms" such as fever and sore throat. Physical examination, including palpation of any enlarged lymph nodes in the neck, or enlarged spleen. The heterophile antibody test is a screening test that gives results within a day, but has significantly less than full sensitivity (70–92%) in the first two weeks after clinical symptoms begin. Serological tests take longer time than the heterophile antibody test, but are more accurate. Physical examination
The presence of an enlarged spleen, and swollen posterior cervical, axillary, and inguinal lymph nodes are the most useful to suspect a diagnosis of infectious mononucleosis.
Precautions
Pioglitazone/metformin should not be used in people with type 1 diabetes or for the treatment of diabetic ketoacidosis and should be used with caution in people with edema. Serum ALT levels should be evaluated prior to the initiation of therapy with combination of pioglitazone and metformin and periodically thereafter per the clinical judgment of the health care professional. Side-effects
The most common side-effects are upper respiratory tract infection, diarrhea, combined edema/peripheral edema and headache, respectively. Most clinical adverse events were similar between groups treated with pioglitazone in combination with metformin and those treated with pioglitazone monotherapy. Contraindications
Pioglitazone/metformin is contraindicated in people with known hypersensitivity to any components of this combination. These combination also contraindicated in renal disease which may also result from conditions, e.g., acute myocardial infarction, sepsis, acute or chronic metabolic acidosis, including diabetic ketoacidosis, with or without coma. Drug interaction
Pioglitazone/metformin may interact with furosemide, nifedipine, cationic drugs (e.g., amiloride, digoxin, morphine, procainamide, quinidine, quinine, ranitidine, triamterene, trimethoprim, and vancomycin) and certain drugs tend to produce hyperglycemia and may lead to loss of glycemic control (e.g., thiazides and other diuretics, corticosteroids, phenothiazines, thyroid products, estrogens, oral contraceptives, phenytoin, nicotinic acid, sympathomimetics, calcium channel blocking drugs, and isoniazid). References
External links
"Metformin hydrochloride mixture with pioglitazone hydrochloride". Drug Information Portal. U.S. National Library of Medicine.