The top hypochondriac fears include fear of disease (disease phobia) and the false belief that you have a disease (disease conviction). Disease phobia was associated with anxiety, while disease conviction was associated with more physical symptoms (Kellner et al., 1992).
Reference:
Hypochondriacal fears and beliefs, anxiety, and somatisation. Kellner R, Hernandez J, Pathak D. Br J Psychiatry. 1992 Apr;160:525-32.