What could cause an acute elevation in platelet levels? I'm a 27 year old female. I was recently diagnosed with Hashimoto's Disease and 2 days ago I had an initial eval with a Hematologist regarding chronic elevating platelet levels over the past few years. My platelets Monday were around 500. Today I woke up with an unquenchable thirst. I have been drinking water non stop. It feels like my mouth is so dry. After drinking a lot of water I wasn't feeling so good so I took my temp, it kept decreasing, although I never felt cold. When it got down to 95.5 I layed down to try to sleep it off. Woke up with a bad headache and pressure in my chest. I went to an urgent care, they ran labs and everything was normal except for my platelet count which is 656. What could cause it to increase by 100 in 2 days? I do not have diabetes, my blood glucose was checked today to rule it out and it was 74. I'm still thirsty and feeling pressure in my chest. I'm supposed to follow up with my Endo and Heme/onc but I would like to know what's going on to ease my mind a little bit. Thank you for your help!