<prompt> Minimum concentration of reduced hemoglobin required for cyanosis is1gmdl3gmdl5gmdl7gmdl  <response>: Cyanosis refers to a bluish discolouration of the skin and mucous membranes resulting from an increased quantity of reduced hemoglobinI.e.,deoxygenated hemoglobinor of hemoglobin derivativeseg.,methemoglobin or sulfhemoglobinin the small blood vessels of those tissues.Cyanosis becomes apparent when the concentration of reduced hemoglobin in capillary blood exceeds 5gmdL. Ref:Harrison s medicine-18th edition page no:288. 