Hello, Welcome to Health Care Magic. I read carefully your query and I understand your concern. The chronic headache and nausea aren’t typically symptoms of hypothyroidism, they are probably the symptoms of the meningiom that you had been diagnosed, and you should go to a neurologist and doing an MRI of head to know it progres. For the hypothyroidism problem you should do TSH blood test to monitor the dosage of your replacement hormonal therapy and go to an endocrinologist. The high value of the MPV maybe is an artifact of an no appropriate storage of the blood sample, but for a better determination I recommend you to do a platelet smear or known as thrombocyte count by an laboratory doctor or hematologist. Hope this answers your question. If you have additional questions or follow up questions then please do not hesitate in writing to us. I will be happy to answer your questions. Kind regard, Dr .Marsida Janko