Abnormal circulating protein concentration Elevated circulating somatostatin concentration The concentration of somatostatin in the blood corculation is above the upper limit of normal. Somatostatin high in blood Somatostatin is a 14 amino acid polypeptide whose principal function is to regulate growth hormone release from the pituitary. Elevated serum and synovial fluid somatostatin levels have been associated with inflammatory responses most notably in rheumatoid arthritis.