Finger tip unit

In medicine, a finger tip unit (FTU) is defined as the amount of ointment, cream or other semi-solid dosage form expressed from a tube with a 5mm diameter nozzle, applied from the distal skin-crease to the tip of the index finger of an adult.[1][2] The "distal skin-crease" is the skin crease over the joint nearest the end of the finger. One FTU is enough to treat an area of skin twice the size of the flat of an adult's hand with the fingers together, i.e. a “handprint”.

One handprint is 0.8% (i.e. approximately 1%) of the total body surface area,[3] and one FTU covers approximately two handprints. As two FTUs are approximately equivalent to 1g of topical application, the “Rule of Hand” states that “4 hand areas = 2 FTU = 1g”.[4]

The FTU is particularly useful when counseling patients with regards to the amount of topical steroid cream they should be applying in order to minimize the side-effects which are associated with their use. The FTU can also be used in children.[5]

Two FTUs are approximately equivalent to 1g of topical steroid.

Dermatology Working Groups in the UK [6] and in Poland [7] have recommended that guidance for use of topical corticosteroids in patient information leaflets should include clear FTU instructions, preferably with images of a FTU and a chart to show the number of units required for specific areas of the body. USA guidelines of care [8] for the management of psoriasis with topical therapies include guidance of amount to be used based on the FTU.

The use of the FTU has been advocated to reduce the variation in usage of topical steroids [9] and to encourage adherence to therapy.[10] The FTU can also be used to guide the use of topical sunscreens.[11] The FTU has been used to standardize the amount of cream being applied in clinical research studies in the UK,[12] Belgium,[13] Turkey,[14] India,[15] Iran,[16] Pakistan [17] and the USA.[18][19]

In the original study in the UK,[20] one FTU weighed 0.49g in men and 0.43g in women. The area covered by one FTU was 312 cm² in men and 257 cm² in women.[21] Very similar results were found in a Mexico study.[22] The weight of an FTU has been recalculated in Japan, relating to the use of 5g tubes of ointment with a much smaller nozzle diameter. [23] The weight of ointment is less if the nozzle diameter is smaller than the standard 5mm.

When a topical drug was used as a foam, the weight of an FTU was 52.5 μg: the area covered by one foam FTU was less than that of an FTU of cream.[24]

References

  1. ↑ Finlay AY, Edwards PH, Harding KG. “Fingertip unit” in dermatology. Lancet 1989; II, 155.
  2. ↑ Long CC, Finlay AY. The fingertip unit: a new practical measure. Clin Exper Dermatol 1991; 16: 444-446.
  3. ↑ Thomas CL, Finlay AY. The “handprint” approximates to 1% of the total body surface area whereas the “palm minus the fingers” does not. British Journal of Dermatology 2007; 157: 1080-1081.
  4. ↑ Long CC, Finlay AY, Averill RW. The rule of hand: 4 hand areas = 2FTU = 1g. Arch Dermatol 1992; 128: 1130-1131.
  5. ↑ Long CC, Mills C, Finlay AY. A practical guide to topical therapy in children. Br J Dermatol 1998; 138: 293-296.
  6. ↑ Bewley A; Dermatology Working Group. Expert consensus: time for a change in the way we advise our patients to use topical corticosteroids. Br J Dermatol 2008; 158: 917-920.
  7. ↑ Kaszuba A, Pastuszka M. Kaszuba A. Glucocorticosteroids in the treatment of dermatological diseases – the recommended standards. Fam Med Forum 2009; 3: 347-358.
  8. ↑ Menter A, Korman NJ, Elmets CA, Feldman SR et al. Guidelines of care for the management of psoriasis and psoriatic arthritis. J Am Acad Dermatol 2009; 60: 643-659.
  9. ↑ McHenry PM, Williams HC, Bingham EA. Management of atopic eczema. Joint workshop of the British Association of Dermatologists and the Royal College of Physicians of London. BMJ 1995;310(6983): 843-847.
  10. ↑ Feldman SR, Horn EJ, Balkrishnan R, Basra MKA, Finlay AY, McCoy D, Menter A, van de Kerkhof P. Psoriasis: improving adherence to therapy. J Am Acad Dermatol 2008; 59: 1009-1016.
  11. ↑ Diffey BL. What can be done to reduce personal ultraviolet radiation exposure? Chapter 13 in: Prevention of skin cancer. Editors Hill DJ, Elwood JM, English DR. Kluwer Academic Publishers, Dordrecht, 2004.
  12. ↑ Cork MJ, Britton J, Butler L, Young S, Murphy R, Keohane SG. Comparison of parent knowledge, therapy utilization and severity of atopic eczema before and after explanation and demonstration of topical therapies by a specialist dermatology nurse. Br J Dermatol 2003; 149: 582-589.
  13. ↑ Letawe C, Pierard-Franchimont C, Pierard GE. Squamometry in rating the efficacy of topical corticosteroids in atopic dermatitis. Eur J Clin Pharmacol 1996; 51: 253-257.
  14. ↑ Karabulut AA, Izol Serel B, Eksioglu HM. A randomized, single-blind, placebo-controlled, split-face study with pimecrolimus cream 1% for papulopustular rosacea. J Eur Acad Dermatol Venereol 2008; 22: 729-734.
  15. ↑ Rai R, Uppal M, Sharma NK, Srinivas CR, Mathew A. Half an hour versus three hour contact of topical steroid (clobetasol propionate). Indian J Dermatol, Venereol and Leprol 2004; 70: 214-216.
  16. ↑ Shohrati M, Davoudi M, Almasi M, Sadr B. Peyman M. Comparative study of Unna’s Boot and betamethasone cream in the treatment of sulfur mustard-related pruritus. Cutan Ocul Toxicol 2007; 26 (4): 303-9.
  17. ↑ Kapadia N, Ghouri S. Efficacy, safety and tolerability of mometasome furoate 0.1% cream, ointment and lotion in childhood eczema. J Pakistan Ass Dermatol 2008; 18; 93-96.
  18. ↑ Safavi K. Serum vitamin A levels in psoriasis: results from the first National Health and Nutrition Examination Survey. Arch Dermatol 1992: 128; 1130-1131.
  19. ↑ Maloney JM, Morman MR, Stewart DM, Tharp MD, Brown JJ, Rajagopalan R. Clobetasol propionate emollient 0.05% in the treatment of atopic dermatitis. Int J Dermatol 1998; 37: 142-144.
  20. ↑ Finlay AY, Edwards PH, Harding KG. “Fingertip unit” in dermatology. Lancet 1989; II, 155.
  21. ↑ Long CC, Finlay AY. The fingertip unit: a new practical measure. Clin Exper Dermatol 1991; 16: 444-446.
  22. ↑ Castanedo-Cazares JP, Torres-Alvarez B, Martinez-Rodriguez A, Diaz-Rosales A, Moncada B. Analysis of the digital unit as reference measurement for the topical prescription in Mexico (in Spanish). Gac Med Mex 2006; 142: 35-38.
  23. ↑ Dekio I, Morita E. The weight of a finger-tip unit of ointment in 5-gram tubes. J Dermatolog Treat 2011; 22: 302-3.
  24. ↑ Feldman SR, Sangha N, Setaluri V. Topical corticosteroid in foam vehicle offers comparable coverage compared with traditional vehicles. J Am Acad Dermatol 2000; 42: 1017-1020.