Once established within a procedure the procedure's altitude limits apply.
eg. A conventional 'break towards' NDB approach with a hold over the aid:
MSA or MEA applies until crossing the aid
Minimum hold altitude applies during the sector entry & hold
Published limiting step down altitudes during the approach
MDA from the last step down limit
Mandatory minimum altitudes during the missed approach
Holding minimum within a missed approach terminating hold, MSA otherwise.