In relation to haematology, this looks a likely candidate:

Thrombopoietin (Tpo), the main regulator of thrombocytopoiesis, is a probable candidate to play a role in the increase in platelet counts that is frequently seen after surgery. In the current study, serial blood samples of patients that underwent major surgery were analysed with respect to Tpo kinetics, platelet turnover and inflammatory cytokines. Platelet Tpo content and plasma Tpo levels rose before platelet counts increased, suggesting that Tpo was indeed responsible for the elevation in platelet counts.
http://www.acor.org/cnet/708415.export


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Note added at 1 hr (2006-09-16 05:30:03 GMT)
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Thrombopoietin (TPO) is a glycoprotein hormone produced mainly by the liver and the kidney that regulates the production of platelets by the bone marrow. It stimulates the production and differentiation of megakaryocytes, the bone marrow cells that fragment into large numbers of platelets[1].
http://en.wikipedia.org/wiki/Thrombopoietin

Thrombopoietin is an investigational or experimental drug that may increase the number of platelets in the bloodstream […] Thrombocytopenia is a common side effect from many common chemotherapy agents. These agents temporarily decrease the production of platelets, as well as white blood cells that fight infection and red blood cells that carry oxygen. Carboplatin is an example of an agent that has a tendency to lower platelet counts. Like other cells of the blood (white blood cells and red blood cells), the number of platelets will generally increase and return to normal over days and weeks following the administration of chemotherapy.
By reducing the severity of platelet-related side effects, thrombopoietin could allow the antitumor medication to be used at higher doses and/or for longer periods of time. Thrombopoietin may also be used in other situations in which patients have low platelet cell counts.
http://www.answers.com/topic/thrombopoietin

Thrombopoietin (TPO) is produced primarily in the liver and secondarily in the ... Approval of Thrombopoietin for clinical use has been delayed because ...
www.familygenetics.net/biology/thrombopoietin.htm


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Note added at 2 hrs (2006-09-16 06:30:04 GMT)
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However, TPO - in this instance at least - is measured in units and not a unitless number, and even if the units here are "understood", the number size is very different:

The TPO level (mean±SD) in ITP patients was mildly elevated (1.86±1.17 fmol/ml) compared to that in normal subjects (0.76±0.21), and was within the normal range in 30% of ITP patients. In contrast, the TPO level in patients with aplastic anaemia was very high, 12.35±6.42 fmol/ml