# Isotopes of lutetium

Naturally occurring lutetium ($_{71}$Lu) is composed of one stable isotope $^{175}$Lu (97.41% natural abundance) and one long-lived radioisotope, $^{176}$Lu with a half-life of 37 billion years (2.59% natural abundance). Forty radioisotopes have been characterized, with the most stable, besides $^{176}$Lu, being $^{174}$Lu with a half-life of 3.31 years, and $^{173}$Lu with a half-life of 1.37 years. All of the remaining radioactive isotopes have half-lives that are less than 9 days, and the majority of these have half-lives that are less than half an hour. This element also has 18 meta states, with the most stable being $^{177m}$Lu (t$_{1/2}$ 160.4 days), $^{174m}$Lu (t$_{1/2}$ 142 days) and $^{178m}$Lu (t$_{1/2}$ 23.1 minutes).
The known isotopes of lutetium range in mass number from 149 to 190. The primary decay mode before the most abundant stable isotope, $^{175}$Lu, is electron capture (with some alpha and positron emission), and the primary mode after is beta emission. The primary decay products before $^{175}$Lu are isotopes of ytterbium and the primary products after are isotopes of hafnium. All isotopes of lutetium are either radioactive or, in the case of $^{175}$Lu, observationally stable, meaning that $^{175}$Lu is predicted to be radioactive but no actual decay has been observed.

## List of isotopes

| Nuclide | Z | N | Isotopic mass (Da) | Half-life | Decay mode | Daughter isotope | Spin and parity | Natural abundance (mole fraction) | Natural abundance (mole fraction) |
| Nuclide | Excitation energy | Excitation energy | Excitation energy | Half-life | Decay mode | Daughter isotope | Spin and parity | Normal proportion | Range of variation |
| $^{149}$Lu | 71 | 78 | | 450+170 −100 ns | p | $^{148}$Yb | 11/2− | |
| $^{150}$Lu | 71 | 79 | 149.97341(32)# | 45(3) ms | p | $^{149}$Yb | (5−) | |
| $^{150m}$Lu | 22(5) keV | 22(5) keV | 22(5) keV | 40(7) μs | p | $^{149}$Yb | (8+) | |
| $^{151}$Lu | 71 | 80 | 150.96747(32)# | 78.4(9) ms | p (?%) | $^{150}$Yb | 11/2− | |
| $^{151}$Lu | 71 | 80 | 150.96747(32)# | 78.4(9) ms | β$^+$ (?%) | $^{151}$Yb | 11/2− | |
| $^{151m}$Lu | 57(4) keV | 57(4) keV | 57(4) keV | 16.0(5) μs | p | $^{150}$Yb | 3/2+ | |
| $^{152}$Lu | 71 | 81 | 151.96412(21)# | 650(70) ms | β$^+$ (85%) | $^{152}$Yb | (4−, 5−, 6−) | |
| $^{152}$Lu | 71 | 81 | 151.96412(21)# | 650(70) ms | β$^+$, p (15%) | $^{151}$Tm | (4−, 5−, 6−) | |
| $^{153}$Lu | 71 | 82 | 152.95880(16) | 0.9(2) s | α (?%) | $^{149}$Tm | 11/2− | |
| $^{153}$Lu | 71 | 82 | 152.95880(16) | 0.9(2) s | β$^+$ (?%) | $^{153}$Yb | 11/2− | |
| $^{153m1}$Lu | 80(5) keV | 80(5) keV | 80(5) keV | 1# s | IT | $^{153}$Lu | 1/2+ | |
| $^{153m2}$Lu | 2502.5(4) keV | 2502.5(4) keV | 2502.5(4) keV | >0.1 μs | IT | $^{153}$Lu | 23/2− | |
| $^{153m3}$Lu | 2632.9(5) keV | 2632.9(5) keV | 2632.9(5) keV | 15(3) μs | IT | $^{153}$Lu | 27/2− | |
| $^{154}$Lu | 71 | 83 | 153.95742(22)# | 1# s | | | (2−) | |
| $^{154m1}$Lu | 62(12) keV | 62(12) keV | 62(12) keV | 1.12(8) s | β$^+$ (?%) | $^{154}$Yb | (9+) | |
| $^{154m1}$Lu | 62(12) keV | 62(12) keV | 62(12) keV | 1.12(8) s | β$^+$p (?%) | $^{153}$Tm | (9+) | |
| $^{154m1}$Lu | 62(12) keV | 62(12) keV | 62(12) keV | 1.12(8) s | β$^+$α (?%) | $^{150}$Er | (9+) | |
| $^{154m2}$Lu | 2724(100)# keV | 2724(100)# keV | 2724(100)# keV | 35(3) μs | IT | $^{154}$Lu | (17+) | |
| $^{155}$Lu | 71 | 84 | 154.954326(21) | 68(2) ms | α (90%) | $^{151}$Tm | 11/2− | |
| $^{155}$Lu | 71 | 84 | 154.954326(21) | 68(2) ms | β$^+$ (10%) | $^{155}$Yb | 11/2− | |
| $^{155m1}$Lu | 21(4) keV | 21(4) keV | 21(4) keV | 138(9) ms | α (76%) | $^{151}$Tm | 1/2+ | |
| $^{155m1}$Lu | 21(4) keV | 21(4) keV | 21(4) keV | 138(9) ms | β$^+$ (24%) | $^{155}$Yb | 1/2+ | |
| $^{155m2}$Lu | 1780.3(18) keV | 1780.3(18) keV | 1780.3(18) keV | 2.69(3) ms | α | $^{151}$Tm | 25/2−# | |
| $^{156}$Lu | 71 | 85 | 155.953087(58) | 494(12) ms | α | $^{152}$Tm | (2)− | |
| $^{156m1}$Lu | 10(250) keV | 10(250) keV | 10(250) keV | 198(2) ms | α | $^{152}$Tm | 10+ | |
| $^{156m2}$Lu | 2611(250) keV | 2611(250) keV | 2611(250) keV | 179(4) ns | IT | $^{156}$Lu | 19− | |
| $^{157}$Lu | 71 | 86 | 156.950145(13) | 7.7(20) s | β$^+$ (?%) | $^{157}$Yb | (1/2+) | |
| $^{157}$Lu | 71 | 86 | 156.950145(13) | 7.7(20) s | α (?%) | $^{153}$Tm | (1/2+) | |
| $^{157m}$Lu | 20.9(20) keV | 20.9(20) keV | 20.9(20) keV | 4.79(12) s | β$^+$ (92.3%) | $^{157}$Yb | (11/2−) | |
| $^{157m}$Lu | 20.9(20) keV | 20.9(20) keV | 20.9(20) keV | 4.79(12) s | α (7.7%) | $^{153}$Tm | (11/2−) | |
| $^{158}$Lu | 71 | 87 | 157.949316(16) | 10.6(3) s | β$^+$ (99.09%) | $^{158}$Yb | (2)− | |
| $^{158}$Lu | 71 | 87 | 157.949316(16) | 10.6(3) s | α (0.91%) | $^{154}$Tm | (2)− | |
| $^{159}$Lu | 71 | 88 | 158.946636(40) | 12.1(10) s | β$^+$ | $^{159}$Yb | 1/2+ | |
| $^{159}$Lu | 71 | 88 | 158.946636(40) | 12.1(10) s | α (rare) | $^{155}$Tm | 1/2+ | |
| $^{160}$Lu | 71 | 89 | 159.946033(61) | 36.1(3) s | β$^+$ | $^{160}$Yb | 2−# | |
| $^{160m}$Lu | 0(100)# keV | 0(100)# keV | 0(100)# keV | 40(1) s | β$^+$ | $^{160}$Yb | | |
| $^{161}$Lu | 71 | 90 | 160.943572(30) | 77(2) s | β$^+$ | $^{161}$Yb | 1/2+ | |
| $^{161m}$Lu | 182(5)# keV | 182(5)# keV | 182(5)# keV | 7.3(4) ms | IT | $^{161}$Lu | (9/2−) | |
| $^{162}$Lu | 71 | 91 | 161.943283(81) | 1.37(2) min | β$^+$ | $^{162}$Yb | 1− | |
| $^{162m1}$Lu | 120(200)# keV | 120(200)# keV | 120(200)# keV | 1.5 min | β$^+$ | $^{162}$Yb | 4−# | |
| $^{162m2}$Lu | 300(200)# keV | 300(200)# keV | 300(200)# keV | 1.9 min | | | 9−# | |
| $^{163}$Lu | 71 | 92 | 162.941179(30) | 3.97(13) min | β$^+$ | $^{163}$Yb | 1/2+ | |
| $^{164}$Lu | 71 | 93 | 163.941339(30) | 3.14(3) min | β$^+$ | $^{164}$Yb | 1− | |
| $^{165}$Lu | 71 | 94 | 164.939407(28) | 10.74(10) min | β$^+$ | $^{165}$Yb | 1/2+ | |
| $^{166}$Lu | 71 | 95 | 165.939859(32) | 2.65(10) min | β$^+$ | $^{166}$Yb | 6− | |
| $^{166m1}$Lu | 34.37(22) keV | 34.37(22) keV | 34.37(22) keV | 1.41(10) min | β$^+$ (58%) | $^{166}$Yb | 3− | |
| $^{166m1}$Lu | 34.37(22) keV | 34.37(22) keV | 34.37(22) keV | 1.41(10) min | IT (42%) | $^{166}$Lu | 3− | |
| $^{166m2}$Lu | 43.0(4) keV | 43.0(4) keV | 43.0(4) keV | 2.12(10) min | β$^+$ (90%) | $^{166}$Yb | 0− | |
| $^{166m2}$Lu | 43.0(4) keV | 43.0(4) keV | 43.0(4) keV | 2.12(10) min | IT (10%) | $^{166}$Lu | 0− | |
| $^{167}$Lu | 71 | 96 | 166.938243(40) | 51.5(10) min | β$^+$ | $^{167}$Yb | 7/2+ | |
| $^{167m}$Lu | 50(40)# keV | 50(40)# keV | 50(40)# keV | >1 min | | | 1/2+ | |
| $^{168}$Lu | 71 | 97 | 167.938730(41) | 5.5(1) min | β$^+$ | $^{168}$Yb | 6− | |
| $^{168m}$Lu | 160(40) keV | 160(40) keV | 160(40) keV | 6.7(4) min | β$^+$ | $^{168}$Yb | 3+ | |
| $^{169}$Lu | 71 | 98 | 168.9376458(32) | 34.06(5) h | β$^+$ | $^{169}$Yb | 7/2+ | |
| $^{169m}$Lu | 29.0(5) keV | 29.0(5) keV | 29.0(5) keV | 160(10) s | IT | $^{169}$Lu | 1/2− | |
| $^{170}$Lu | 71 | 99 | 169.938479(18) | 2.012(30) d | β$^+$ | $^{170}$Yb | 0+ | |
| $^{170m}$Lu | 92.91(9) keV | 92.91(9) keV | 92.91(9) keV | 670(100) ms | IT | $^{170}$Lu | 4− | |
| $^{171}$Lu | 71 | 100 | 170.9379186(20) | 8.247(23) d | β$^+$ | $^{171}$Yb | 7/2+ | |
| $^{171m}$Lu | 71.13(8) keV | 71.13(8) keV | 71.13(8) keV | 79(2) s | IT | $^{171}$Lu | 1/2− | |
| $^{172}$Lu | 71 | 101 | 171.9390913(25) | 6.70(3) d | β$^+$ | $^{172}$Yb | 4− | |
| $^{172m1}$Lu | 41.86(4) keV | 41.86(4) keV | 41.86(4) keV | 3.7(5) min | IT | $^{172}$Lu | 1− | |
| $^{172m2}$Lu | 65.79(4) keV | 65.79(4) keV | 65.79(4) keV | 332(20) ns | IT | $^{172}$Lu | (1)+ | |
| $^{172m3}$Lu | 109.41(10) keV | 109.41(10) keV | 109.41(10) keV | 440(12) μs | IT | $^{172}$Lu | (1)+ | |
| $^{172m4}$Lu | 213.57(17) keV | 213.57(17) keV | 213.57(17) keV | 150 ns | IT | $^{172}$Lu | (6−) | |
| $^{173}$Lu | 71 | 102 | 172.9389357(17) | 1.37(1) y | EC | $^{173}$Yb | 7/2+ | |
| $^{173m}$Lu | 123.672(13) keV | 123.672(13) keV | 123.672(13) keV | 74.2(10) μs | IT | $^{173}$Lu | 5/2− | |
| $^{174}$Lu | 71 | 103 | 173.9403428(17) | 3.31(5) y | β$^+$ | $^{174}$Yb | 1− | |
| $^{174m1}$Lu | 170.83(5) keV | 170.83(5) keV | 170.83(5) keV | 142(2) d | IT (99.38%) | $^{174}$Lu | 6− | |
| $^{174m1}$Lu | 170.83(5) keV | 170.83(5) keV | 170.83(5) keV | 142(2) d | EC (0.62%) | $^{174}$Yb | 6− | |
| $^{174m2}$Lu | 240.818(4) keV | 240.818(4) keV | 240.818(4) keV | 395(15) ns | IT | $^{174}$Lu | 3+ | |
| $^{174m3}$Lu | 365.183(6) keV | 365.183(6) keV | 365.183(6) keV | 145(3) ns | IT | $^{174}$Lu | 4− | |
| $^{174m4}$Lu | 1855.7(5) keV | 1855.7(5) keV | 1855.7(5) keV | 194(24) ns | IT | $^{174}$Lu | 13+ | |
| $^{174m5}$Lu | 4068.4(9) keV | 4068.4(9) keV | 4068.4(9) keV | 97(10) ns | IT | $^{174}$Lu | (21+) | |
| $^{174m6}$Lu | 5849.6(9) keV | 5849.6(9) keV | 5849.6(9) keV | 242(19) ns | IT | $^{174}$Lu | (26−) | |
| $^{175}$Lu | 71 | 104 | 174.9407772(13) | Observationally stable | Observationally stable | Observationally stable | 7/2+ | 0.97401(13) |
| $^{175m1}$Lu | 353.48(13) keV | 353.48(13) keV | 353.48(13) keV | 1.49(7) μs | IT | $^{175}$Lu | 5/2− | |
| $^{175m2}$Lu | 1392.4(4) keV | 1392.4(4) keV | 1392.4(4) keV | 984(30) μs | IT | $^{175}$Lu | 19/2+ | |
| $^{176}$Lu | 71 | 105 | 175.9426917(13) | 3.701(17)×10$^{10}$ y | β$^−$ (99.55(26)%) | $^{176}$Hf | 7− | 0.02599(13) |
| $^{176}$Lu | 71 | 105 | 175.9426917(13) | 3.701(17)×10$^{10}$ y | EC (0.45(26)%) | $^{176}$Yb | 7− | 0.02599(13) |
| $^{176m1}$Lu | 122.845(4) keV | 122.845(4) keV | 122.845(4) keV | 3.664(19) h | β$^−$ (99.90%) | $^{176}$Hf | 1− | |
| $^{176m1}$Lu | 122.845(4) keV | 122.845(4) keV | 122.845(4) keV | 3.664(19) h | EC (0.095%) | $^{176}$Yb | 1− | |
| $^{176m2}$Lu | 1514.5(5) keV | 1514.5(5) keV | 1514.5(5) keV | 312(69) ns | IT | $^{176}$Lu | 12+ | |
| $^{176m3}$Lu | 1587.8(6) keV | 1587.8(6) keV | 1587.8(6) keV | 40(3) μs | IT | $^{176}$Lu | 14+ | |
| $^{177}$Lu | 71 | 106 | 176.9437636(13) | 6.6443(9) d | β$^−$ | $^{177}$Hf | 7/2+ | |
| $^{177m1}$Lu | 150.3984(10) keV | 150.3984(10) keV | 150.3984(10) keV | 130.1(24) ns | IT | $^{177}$Lu | 9/2− | |
| $^{177m2}$Lu | 569.6721(15) keV | 569.6721(15) keV | 569.6721(15) keV | 155(7) μs | IT | $^{177}$Lu | 1/2+ | |
| $^{177m3}$Lu | 970.1757(24) keV | 970.1757(24) keV | 970.1757(24) keV | 160.4(3) d | β$^−$ (77.30%) | $^{177}$Hf | 23/2− | |
| $^{177m3}$Lu | 970.1757(24) keV | 970.1757(24) keV | 970.1757(24) keV | 160.4(3) d | IT (22.70%) | $^{177}$Lu | 23/2− | |
| $^{177m4}$Lu | 2771.7(5) keV | 2771.7(5) keV | 2771.7(5) keV | 625(62) ns | IT | $^{177}$Lu | 33/2+ | |
| $^{177m5}$Lu | 3530.4(6) keV | 3530.4(6) keV | 3530.4(6) keV | 6(2) μs | IT | $^{177}$Lu | 39/2− | |
| $^{178}$Lu | 71 | 107 | 177.9459601(24) | 28.4(2) min | β$^−$ | $^{178}$Hf | 1+ | |
| $^{178m}$Lu | 123.8(26) keV | 123.8(26) keV | 123.8(26) keV | 23.1(3) min | β$^−$ | $^{178}$Hf | 9− | |
| $^{179}$Lu | 71 | 108 | 178.9473330(55) | 4.59(6) h | β$^−$ | $^{179}$Hf | 7/2+ | |
| $^{179m}$Lu | 592.4(4) keV | 592.4(4) keV | 592.4(4) keV | 3.1(9) ms | IT | $^{179}$Lu | 1/2+ | |
| $^{180}$Lu | 71 | 109 | 179.949891(76) | 5.7(1) min | β$^−$ | $^{180}$Hf | 5+ | |
| $^{180m1}$Lu | 13.9(3) keV | 13.9(3) keV | 13.9(3) keV | ~1 s | | | 3− | |
| $^{180m2}$Lu | 624.0(5) keV | 624.0(5) keV | 624.0(5) keV | >1 ms | IT | $^{180}$Lu | (9−) | |
| $^{181}$Lu | 71 | 110 | 180.95191(14) | 3.5(3) min | β$^−$ | $^{181}$Hf | 7/2+# | |
| $^{182}$Lu | 71 | 111 | 181.95516(22)# | 2.0(2) min | β$^−$ | $^{182}$Hf | 1−# | |
| $^{183}$Lu | 71 | 112 | 182.957363(86) | 58(4) s | β$^−$ | $^{183}$Hf | 7/2+# | |
| $^{184}$Lu | 71 | 113 | 183.96103(22)# | 20(3) s | β$^−$ | $^{184}$Hf | (3+) | |
| $^{185}$Lu | 71 | 114 | 184.96354(32)# | 20# s [>300 ns] | | | 7/2+# | |
| $^{186}$Lu | 71 | 115 | 185.96745(43)# | 6# s [>300 ns] | | | | |
| $^{187}$Lu | 71 | 116 | 186.97019(43)# | 7# s [>300 ns] | | | 7/2+# | |
| $^{188}$Lu | 71 | 117 | 187.97443(43)# | 1# s [>300 ns] | | | | |
| $^{189}$Lu | 71 | 118 | | | | | | |
| $^{190}$Lu | 71 | 119 | | | | | | |
| This table header & footer: view ||||||||||
* ↑ $^m$Lu – Excited nuclear isomer.
* ↑ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
* ↑ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
* ↑ Bold half-life – nearly stable, half-life longer than age of universe.
* 1 2 3 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
* ↑ Modes of decay: EC:Electron capture IT:Isomeric transition p:Proton emission
* ↑ Bold symbol as daughter – Daughter product is stable.
* ↑ ( ) spin value – Indicates spin with weak assignment arguments.
* 1 2 3 Order of ground state and isomer is uncertain.
* ↑ Discovery of this isotope is disputed.
* ↑ Believed to undergo α decay to $^{171}$Tm
* ↑ primordial radionuclide
* ↑ Used in lutetium-hafnium dating

## Lutetium-177

Lutetium ($^{177}$Lu) chloride, sold under the brand name Lumark among others, is used for radiolabeling other medicines, either as an anti-cancer therapy or for scintigraphy (medical radio-imaging). Its most common side effects are anaemia (low red blood cell counts), thrombocytopenia (low blood platelet counts), leucopenia (low white blood cell counts), lymphopenia (low levels of lymphocytes, a particular type of white blood cell), nausea (feeling sick), vomiting and mild and temporary hair loss.