Methods and controls for monitoring assay quality and accuracy in parathyroid hormone measurement

A parathyroid hormone (PTH) assay control, comprising a composition having a known concentration of a whole PTH component mixed with a known concentration of a PTH fragment component, comprising:

• a) a whole PTH component having an amino acid sequence set forth in SEQ ID NO:1 (PTH1-84), wherein the N-terminal amino acid residue of the PTH molecule must be intact;
• and
• b) a PTH fragment component having an amino acid sequence set forth in SEQ ID NO:1 (PTH1-84), wherein the N-terminal amino acid residue of the PTH fragment starts at any position spanning position 2 through position 33 of the PTH1-84, the C-terminal amino acid residue of the PTH fragment ends at any position spanning position 35 through position 84 of the PTH1-84;
• and the PTH fragment has a minimal length of four amino acid residues;
• wherein the ratio of the whole PTH component to the PTH fragment component ranges between about 1% to about 99%,
• wherein said composition further comprises a protein matrix base,
• and wherein said assay control is lyophilized.