降血钙素

• 阝(mound; hill)RADICAL
• 夅(descend; go down)PHONETIC

Going down from a high hill peak is the meaning of the character 降.

• 皿(bowl; dish)RADICAL
• 丿(drop of blood; blood drop)ASSOCIATIVE

Blood is a small red drop of liquid flowing down into a bowl—picturing blood dripping into a vessel.

• 釒(metal)RADICAL
• 丐(beg; solicit alms)PHONETIC

The metal element for "thing" is calcium, the crucial skeletal element.

• 糸(silk thread; filament)RADICAL
• 龶(coarse undyed thread bundle; top part of thread)ASSOCIATIVE

Raw silk that hasn't been dyed suggests the meaning of pure, simple, and basic.