So, we recommend that the certifier review the decedents medical history to identify the condition that started the sequence of events leading to death, without which the death would not have occurred at the same time or same manner. 

Chronic medical conditions - such as Alzheimer's, dementia, diabetes mellitus and stroke due to hypertension - are often appropriate underlying causes.  Your knowledge may be limited to the extent of the patient’s medical work up, and so it may be appropriate to use terms like “possible”, “probable” or “suspected” to indicate that the diagnosis is not confirmed.