Pancreatic Polypeptide Unit Converter
Pancreatic Polypeptide Unit Converter
Convert pancreatic polypeptide between pg/mL, ng/L and pmol/L, with the molar factor derived from the peptide’s own sequence — and read why the reference limit rises 20 pg/mL every decade, and why a raised PP is far more often renal impairment or a non-fasting sample than a tumour.
Pancreatic polypeptide converter
Mass ⇄ molarPancreatic polypeptide 180 pg/mL on a fasting EDTA plasma from a 42-year-old
Where the molar factor comes from
pmol/L = pg/mL × 0.239137
derived from a molecular weight of 4,181.7 Da for the 36-residue amidated peptide
- the peptide
- human pancreatic polypeptide is UniProt P01298 residues 30–65, APLEPVYPGDNATPEQMAQYAADLRRYINMLTRPRY, with the C-terminal tyrosine amidated. Thirty-six residues, no glycosylation, no polymerisation
- 4,181.7 Da
- the average mass. Summing the residue masses of that sequence and adding water gives 4,182.74 for the free acid; amidating the C-terminus subtracts 0.98 to give 4,181.76. A commercial synthetic standard of the same peptide is specified as C₁₈₅H₂₈₇N₅₃O₅₄S₂, MW 4,181.7 — two independent routes to the same number
- × 0.239137
- 1 pg/mL is 10⁻⁹ g/L; 10⁻⁹ ÷ 4,181.7 = 2.39137 × 10⁻¹³ mol/L = 0.239137 pmol/L. So 1,000 ÷ 4,181.7 = 0.239137 pmol/L per pg/mL, and the inverse is 4.1817 pg/mL per pmol/L
- what the factor does NOT do
- it converts one assay’s number between scales. It does not make two assays’ numbers comparable: PP immunoassays are calibrated against their own preparations, and a result from one laboratory should not be compared with a result from another or plotted on the same trend line
- why some peptides get no molar unit
- copeptin is variably glycosylated and adiponectin circulates as a polymer, so neither has a single molar mass and neither carries a molar conversion on this site. Pancreatic polypeptide is a plain unmodified peptide, which is why it does
Worked example
Pancreatic polypeptide 180 pg/mL on a fasting EDTA plasma from a 42-year-old
180 pg/mL = 180 ng/L — the same number in the other mass convention
180 × 0.239137 = 43.04 pmol/L
Against the 40–49 year upper limit of 270 pg/mL (64.57 pmol/L) this is comfortably inside the range, and the report would not flag it
Change the age band to 20–29 and the limit falls to 228 pg/mL; the same 180 pg/mL is still normal, but a value of 250 would be normal in a 42-year-old and raised in a 25-year-old
The limit rises roughly 20 pg/mL per decade, so an age-blind reference range is the commonest reason a PP looks abnormal when it is not
Why the reference limit is banded by age
| Age | Upper limit (pg/mL) | Upper limit (pmol/L) |
|---|---|---|
| 20–29 years | 228 | 54.52 |
| 30–39 years | 249 | 59.55 |
| 40–49 years | 270 | 64.57 |
| 50–59 years | 291 | 69.59 |
| 60–69 years | 312 | 74.61 |
| 70–79 years | 332 | 79.39 |
| Under 20 and 80 and over | Not established | Not established |
What raises pancreatic polypeptide, and how little it proves
| Cause | Direction | Comment |
|---|---|---|
| A non-fasting sample | Raised | PP rises within 30 to 90 minutes of a meal and stays up; even sham feeding raises it by more than 200 pg/mL through vagal stimulation. An 8-hour fast is mandatory |
| Chronic kidney disease | Raised | Total immunoreactive PP runs close to ten times higher than normal, chiefly in the 10,000 and 4,200 dalton components |
| Increasing age | Raised | Roughly 20 pg/mL per decade, which is why the reference limit is banded |
| Hypoglycaemia and exercise | Raised | Both stimulate PP release through vagal pathways |
| Pancreatic neuroendocrine tumours | Raised in some | Area under the curve 0.64, sensitivity 0.36, specificity 0.74 for pancreatic NETs in MEN1 |
| Extensive loss of pancreatic tissue | Low | Chronic pancreatitis and pancreatic resection reduce basal PP and blunt the response to feeding |
| Atropine and somatostatin analogues | Low | Both block the vagal drive to PP secretion |
A clean molar conversion, and a dirty clinical signal
Pancreatic polypeptide is a 36-residue peptide secreted by the PP cells of the pancreatic islets, concentrated in the head of the pancreas and in the uncinate process. Its release is almost entirely vagally driven: a meal raises it within half an hour, and so does the sight and smell of food without any being eaten, which is why a sham-feeding test was once used to check the completeness of a vagotomy. Hypoglycaemia and exercise raise it too. Somatostatin and atropine suppress it. None of that is under the patient’s conscious control, which is why the specimen requirement — an eight-hour fast, EDTA plasma, on ice, separated and frozen promptly — carries more weight here than the assay does.
The unit conversion is one of the more straightforward on this site, and worth setting out because several related peptides do not get one. Picograms per millilitre and nanograms per litre are the same concentration. For the molar scale, human pancreatic polypeptide is UniProt P01298 residues 30 to 65, a single unmodified chain with an amidated C-terminal tyrosine and an average mass of 4,181.7 daltons; dividing 1,000 by that gives 0.239137 pmol/L for each pg/mL. Copeptin gets no molar unit on this site because its glycosylation varies, and adiponectin gets none because it circulates as a polymer rather than as its monomer. Pancreatic polypeptide has neither problem.
What the molar factor cannot repair is comparability. PP immunoassays are calibrated against their own preparations, and different methods do not produce interchangeable numbers, so a result should not be compared with one from another laboratory or plotted on the same trend line as one. The reference interval is not a single figure either: it rises by roughly 20 pg/mL per decade, from below 228 pg/mL in the twenties to below 332 pg/mL in the seventies, and it is not established under 20 or at 80 and over. A laboratory reporting against a single adult range will make the young look abnormal and the old look reassuring.
Clinically, the interest in PP is that PP-secreting tumours exist and that raised PP occurs in pancreatic neuroendocrine tumours, including in multiple endocrine neoplasia type 1. The difficulty is that raised PP occurs in a great deal else. Chronic kidney disease raises total immunoreactive PP roughly tenfold, because the peptide and its fragments are cleared renally. Age raises it steadily. A non-fasting sample raises it substantially. Against pancreatic neuroendocrine tumours in MEN1, PP achieved an area under the curve of 0.64 with a sensitivity of 0.36 and a specificity of 0.74 — barely a third of tumours detected — and the authors concluded that the accuracy of PP, chromogranin A and glucagon for this purpose is low. A raised PP is a reason to check the specimen, the kidney function and the patient’s age before it is a reason to image the pancreas.
Frequently asked questions
How do I convert pancreatic polypeptide from pg/mL to pmol/L?
Multiply by 0.239137, from a molecular weight of 4,181.7 daltons for the 36-residue amidated peptide. A PP of 180 pg/mL is 43.04 pmol/L. Picograms per millilitre and nanograms per litre are the same number, so no conversion is needed between those two.
What is a normal pancreatic polypeptide level?
It depends on age. One widely used laboratory quotes upper limits of 228 pg/mL at 20–29 years rising to 332 pg/mL at 70–79, an increase of roughly 20 pg/mL per decade, with no interval established below 20 or at 80 and over. The sample must be fasting: eating raises PP within half an hour and produces a falsely high result.
Does a raised pancreatic polypeptide mean a pancreatic tumour?
Usually not. Chronic kidney disease raises total immunoreactive PP about tenfold, a non-fasting sample raises it substantially, and the reference limit rises with age. As a marker for pancreatic neuroendocrine tumours in MEN1, PP had an area under the curve of 0.64, a sensitivity of 0.36 and a specificity of 0.74 — it misses roughly two-thirds of tumours.
Why does pancreatic polypeptide have a molar conversion when copeptin does not?
Because it is a single unmodified 36-residue peptide with one molar mass. Copeptin is a variably glycosylated glycopeptide, so the measurand has no single molecular weight, and adiponectin circulates as trimers, hexamers and high-molecular-weight multimers rather than as its monomer. Neither can be converted to a molar unit honestly; pancreatic polypeptide can.
How should the sample be collected?
After an eight-hour fast, into EDTA, placed on wet ice immediately and kept cold, then centrifuged, aliquoted into plastic and frozen. A non-fasting specimen is the commonest cause of a falsely raised result, and even the smell of food raises PP through vagal stimulation.
Related calculators
References
- UniProt Consortium. P01298 (PAHO_HUMAN), pancreatic polypeptide prohormone — chain “pancreatic hormone”, residues 30–65, C-terminal tyrosine amide. Accessed 2026.
- GenScript. RP10398: pancreatic polypeptide, human — APLEPVYPGDNATPEQMAQYAADLRRYINMLTRPRY-NH₂, C₁₈₅H₂₈₇N₅₃O₅₄S₂, MW 4181.7. Accessed 2026.
- Mayo Clinic Laboratories. Test 8014 (HPP): Pancreatic Polypeptide, Plasma — age-banded upper limits 228–332 pg/mL, rising approximately 20 pg/mL per decade; 8-hour fast, EDTA plasma on ice. Accessed 2026.
- de Laat JM, Pieterman CRC, Weijmans M, et al. Low accuracy of tumor markers for diagnosing pancreatic neuroendocrine tumors in multiple endocrine neoplasia type 1 patients. J Clin Endocrinol Metab. 2013;98(10):4143–4151.
- Garrote FJ, Rovira A, Casado S, Hernando L, Castrillo JM, Valverde I. Immunoreactive pancreatic polypeptide components in plasma from normal subjects and patients with chronic renal failure in basal and postprandial conditions. Metabolism. 1984;33(3):244–249.
Medical Disclaimer: The tools and content provided here are for educational and reference purposes only. They are not intended to substitute for professional medical advice, diagnosis, or treatment. Clinical decisions should always be based on the comprehensive assessment of a qualified healthcare professional.